Genera.

2. Equivalves, having a Foot fitted for crawling, without tubes.

Anodontites. Uva.

3. Equivalves with a Foot constructed for spinning, without tubes.

Lima. Perna. Avicula, comprehending avicula and malleus. Mytilus, comprehending mytilus, and nodosus. Pinna.

4. Having tubes in the cloke, serving for an anus, and for respiration, and a Foot frequently fitted for spinning.

Tellina. Cardium, comprehending cardium and ficcardia. Mactra, comprehending mastra, lustraria, and crafatella. Venus, comprehending venus, meretrix, cyclas, paphia, and capsia. Donax. Chama, comprehending cardia, tridacna, and hippopus. Arca, comprehending arca, pertunculus, and nucula.

β. Open at one extremity, which is perforated by the foot, and prolonged towards the other end into a double tube.

Solen, comprehending solen and sanguilunaria. Mya, comprehending mya, glycineris, and cyrtodaria. Pholas, comprehending pholas and gienia. Teredo, comprehending teredo and fistulana.

γ. Open before, having neither foot nor tubes, but two ciliated arms rolled into a spiral form.

Terebratula, comprehending terebratula, calcoola, and hyalaea. Lingula. Orbicula.

δ. Open before, having neither feet nor tubes, except one proceeding from the body, and furnished with feelers that are horny, articulated, and arranged in pairs.

Anatifa. Balanus.

II. WORMS.

A. Having external organs fitted for respiration.

a. Furnished with bristles on the side of the body.

Aphrodita. Terebella. Nereis. Serpula. Penicillus. Siliquaria. Amphitrite. Dentalium.

B. Having no external organs of respiration.

a. With bristles on the sides of the body.

Nais. Lumbricus. Thalosoma.

b. Having no bristles on the sides of the body.

Hirudo. Fasciola. Planaria. Gordius.

Cuvier is uncertain whether he should place the following genera in the same class with the preceding, or arrange them under a new class, next to the zoophytes.

Family 1.

Tenia. Hydatigena. Ligula. Linguatula.

Family 2.

Ascaris, and the other intestinalia.

III. ZOOPHYTES.

A. Not attached.

a. Having a calcareous or leathery covering, and the intestines floating in the internal cavity. Echinodermata.

Echinus, comprehending echinus, brissus, and spatagus. Asterias. Holothuria. Sipunculus.

b. Having a fleshy or gelatinous covering, and the intestines adhering within the body. Urtica marina.

Actinia, comprehending actinia and zanthus. Medusa, comprehending medusa, beroë, and rhizostoma.

c. Very small, and found swimming in liquors. Infusoria.

Rotifer. Brachionus. Trichocercus. Trichoda. Leucophorus, and the rest of the animalcula infusoria.

c. Having a gelatinous body, and propagating by floats or branches. Polypa.

Hydra. Vorticella.

B. Attached to a solid trunk.

c. Having the medullary substance traversing a horny axis. axis, and terminating the branches, in the form of Polypes. Zoophyta properly so called.

Floscularia. Tubularia. Capsularia. Sertularia.

b. Having the polypes not connected to a medullary axis, but each inclosed in a horny or calcareous cell. Ectocara.

Cellularia. Flustra. Corallina.

c. Having the solid axis covered with sensile flesh, from the hollows of which the polypes proceed. Ceratophyta.

Antipathes. Gorgonia. Corallium. Isis. Pennatula. Verticillum. Umbellula.

Since the publication of these tables, M. Cuvier has made several alterations and additions to the class of Mollusca, which are the subject of several excellent memoirs published in the Annales de Museum National; in particular he has formed a new order in this class, to which he gives the following characters. Body free, swimming; head distinct; having no other member but fins. In this order he arranges three genera, the old genus Clion, and two new ones, which he calls Hyale and Pneumoderme.

As the arrangement of Linnaeus is still that which is most generally received, especially in this country, and is therefore most familiar to our readers, we shall follow it in this article.

GENERIC CHARACTERS.

Ordo I. INTESTINA; animalia simplicia, nuda, aratus desituta.

* Intra alia animalia decentia, oculis nullis.

Gen. 1. Ascaris. Corpus teres, utrinque attenuatum; capite trinodi. 2. Trichuris. Corpus teres, posterius filiforme; capite rostrato. 3. Filaria. Corpus filiforme totum. 4. Uncinaria. Corpus filiforme, elasticum; capite labiato, labii membranacei; cauda (femineae) aciformi, (maris) uncis duobus vesicis pellucide inclusis armata. 5. Scolex. Corpus minimum, gelatinosum, opacum; capite exsertili et retraibili, auriculis 4 pellucidis. 6. Ligula. Corpus lineare, æquale, elongatum. 7. Linguatula. Corpus depressum, oblongum; ore anteriori oulis 4 cincto. 8. Strongylus. Corpus teres, elongatum; anterius globoso-truncatum, apertura circulari margine ciliata; posterius (femineae) acuminatum, (maris) cucullatum. 9. Echinorhynchus. Corpus teres; proboscide cylindrica retractili aculeis uncinate coronata. 10. Hæruca. Corpus teres; capite aculeis coronato. 11. Cucullanus. Corpus posterius acuminatum; anterius obtusum; ore orbiculari. 12. Caryophyllæus. Corpus teres, læve, ore ample. 13. Fasciola. Corpus depressum, ovatum, poro terminali et laterali.

Order I. INTESTINA; animals simple, naked, and destitute of limbs.

* Living within other animals, without eyes.

A. Body round, tapering both ways; head furnished with three protuberances. T. Body round, filiform behind; head furnished with a proboscis. F. Body entirely filiform. U. Body filiform, elastic; head with membranaceous angular lips; tail of the female needle-shaped, of the male armed with two hooks inclosed in a pellucid vesicle. S. Body minute, gelatinous, opake; head exsertile and retractile, with 4 pellucid auricles. L. Body linear, equal, and long. L. Body depressed, oblong; mouth placed on the fore part, and surrounded with 4 palpiages. S. Body round, long; the fore part globular and truncate, with a circular aperture fringed at the margin; hind part of the female pointed, of the male hooded. E. Body round; proboscis cylindrical, retractile, and crowned with hooked prickles. H. Body round; head crowned with prickles. C. Body pointed behind; the fore part obtuse, with an orbicular mouth. C. Body round, smooth, with a large dilated mouth. F. Body depressed, ovate, with a terminal and lateral pore. Chap. I.

** HELMINTHOLOGY. **

14. Tænia. Corpus articulatum, depressum; anterius tubulo 4-fido instructum.

15. Furia. Corpus lineare, aculeis reflexis, utrinque ciliatum.

** Extra alla animalia habitantia.**

† Poro laterali nullo.

16. Gordius. Corpus æquale, filiforme totum, teres, lave.

17. Hirudo. Corpus anterius et posterius truncatum, ore caudaque progrediendo dilatata.

‡ Poro laterali pertusa.

18. Lumbricus. Corpus teres, annulatum; aculeis conditis.

19. Sipunculus. Corpus teres, rostro cylindrico angustato.

20. Planaria. Corpus depressum, poro ventrali.

* Ore supero.

Of the mol-Ordo II. MOLLUSCA. Animalia simplicia, ar-lufca.

21. Actinia. Apertura unica communi, dilatabili, nuda, bafi affixa.

22. Clava. Apertura unica communi, dilatabili, verticali, tentaculis clavatis cincta.

23. Pedicellaria. Corpus pedunculatum, fixum; pedunculo rigido.

24. Mammalia. Apertura unica, cirris nullis, lævis.

25. Ascidia. Aperturis duabus, altera humiliori affixa.

26. Salpa. Aperturis duabus, utraque terminali.

27. Dagysia. Aperturis duabus; corpus angulatum.

** Ore antico.**

28. Pterotrachea. Corpus pervium, gelatinofum, pinna mobili ad abdomen vel caudam.

29. Derris. Corpus teres, acuminatum articulatum; tentacula 2.

*** Corpore pertuso foraminula lateralii.

30. Limax. Tentacula 4. Anus communis cum poro laterali.

31. Lapygia. Tentacula 4; anus supra posteriora.

32. Doris. Tentacula 2; anus supra posteriora.

33. Tethis. Foramina lateralia sinistra gemina.

**** Corpore tentaculis anticis cincto.

34. Holothuria. Tentacula carnofa.

35. Terebella. Tentacula capillaria.

***** Corpore brachiata.

36. Triton. Brachia 12, bipartita, quibusdam cheliferis.

T. Body flat, jointed, furnished before with 4 ori-fices.

F. Body linear, with each side ciliated with reflected prickles.

** Not inhabiting other animals.**

† Having no lateral pore.

G. Body equal, filiform, round, and smooth.

H. Body truncate at each extremity; head and tail dilated when in motion.

‡ Perforated with a lateral pore.

L. Body round, annulate; furnished with minute hidden prickles.

S. Body round, with a cylindrical mouth, narrower than the head.

P. Body flattened, with a ventral pore.

Order II. MOLLUSCA. Animals simple, furnished with limbs.

* With the mouth placed above.

A. Body fixed, with a single terminal dilatable aperture surrounded by tentacula.

C. Body fixed, with a single dilatable vertical aperture, surrounded with clavate tentacula.

P. Body fixed and furnished with a rigid peduncle.

M. Body loofe, smooth, with a single aperture without cirri.

A. Body fixed, with two apertures, one of which is terminal, the other placed a little beneath.

S. Body loofe, with two apertures, one at each end.

D. Body loofe, angular, open at each end.

** Mouth placed before.**

P. Body pervious, gelatinous, with a moveable fin at the head or tail.

D. Body round, tapering, articulate; feelers 2.

*** Body with a lateral perforation.

L. Feelers 4; vent common with the lateral pore.

L. Feelers 4; vent placed above the lower extremity.

D. Feelers 2; vent above the lower extremities.

T. Body with two small pores on the left side.

**** Body surrounded with feelers on the fore part.

H. Feelers flebhy.

T. Feelers capillary.

***** Body furnished with arms.

T. Arms 12, divided, some of them cheliferous. 37. Sepia. Brachia 8—10; instrutha cotylis. 38. Clion. Brachia 2, alifornia, extensa. 39. Onchidium. Brachia 2, dilata ad latera capitis. 40. Lobaria. Corpus supra convexum, subtus planum, lobatum. 41. Lernaea. Brachia 2—3, teritia, tenua. 42. Scyllae. Brachia 6, paribus remotis.

****** Corpore pedato.

43. Aphrodita. Corpus ovale, ocellatum; tentacula duo, fctacea, annulatum. 44. Amphitrite. Corpus tubo extrufum, annulatum; tentacula pinnata, oculi o. 45. Spio. Corpus tubo extrufum, articulatum; tentacula duo simplicia; oculi duo. 46. Nereis. Corpus elongatum repens; pedunculis lateralibus pennicillatis; tentacula simplicia. 47. Naïs. Corpus elongatum, repens; pedunculis fctaceis simplicibus; tentacula nulla; oculi nulli vel 2.

+++ Ore infero, utplurimum centrale.

48. Physophora. Corpus gelatinosum, è vesicula æcrea pendens. 49. Medusa. Corpus gelatinosum, leve. 50. Lucernaria. Corpus gelatinosum, rugosum, brachiatus. 51. Asterias. Coriaceum, muricatum. 52. Echinus. Corpus crustaceum, aculeatum.

Ordo IV. Zoophyta. Animalia composita, more vegetabilium, efflorescentia.

* Stirpe calcarea. Lithophyta.

53. Tubipora. Corallium tubis cylindricis. 54. Madripora. Corallium, stellis concavis. 55. Millepora. Corallium, poris subulatis. 56. Cellepora. Corallium, cellulis cavis. 57. Isis. Stirps lapidea.

** Stirpe molliore.

58. Antipathes. Stirps cornea, spinulis obsita, carne gelatinosa testa. 59. Gorgonia. Stirps cornea, carne cellulosa seu valculo testa. 60. Alcyonium. Stirps suberosa. 61. Spongia. Stirps stipula, flexilis, bibula. 62. Flustra. Stirps porosiflora. 63. Tubularia. Stirps tubularis, filiformis. 64. Corallina. Stirps articulis filiformibus calcareis. 65. Sertularia. Stirps articulis filiformibus fibrofis. 66. Pennatula. Stirps coriacea, penniformis. 67. Hydra. Stirps medullofa, nuda.

S. Arms 8—10, beset with suckers. C. Arms 2, dilated, extended like wings. O. Arms 2, dilated, and placed at the sides of the head. L. Body convex above, flat below, lobate. L. Arms 2—3, round and slender. S. Arms 6, each pair at a distance.

****** Body furnished with feet.

A. Body oval, furnished with eyes; feelers 2, fetaceous, annulate. A. Body proceeding from a tube, and annulate; feelers feathered; eyes wanting. S. Body proceeding from a tube, and jointed; feelers 2, simple; eyes 2. N. Body long, creeping, with lateral pencilled peduncles; feelers simple. N. Body long, creeping; peduncles furnished with simple brittle; feelers none; eyes 0 or 2.

+++ Mouth beneath, commonly central.

P. Body gelatinous, hanging by an air bubble. M. Body gelatinous, smooth. L. Body gelatinous, wrinkled, furnished with arms. A. Body coriaceous, flat, generally radiate and mucicate with papillæ. E. Body crustaceous, and covered with moveable spines.

Order IV. Zoophytes. Compound animals, shooting up like vegetables.

* With a calcareous stem. Lithophyta.

T. Coral, with cylindrical tubes. M. Coral, with concave stars. M. Coral, with tubulate pores. C. Coral, with hollow cells. I. Stem stony.

** With a softer stem.

A. Stem horny, beset with small spines, and covered with a fleety gelatinous coat. G. Stem horny, and covered with a cellular or flethy valcular coat. A. Stem like cork. S. Stem stringy, flexible, and bibulous. F. Stem extremely porous. T. Stem tubular, filiform. C. Stem jointed, filiform, calcareous. S. Stem jointed, filiform, fibrous. P. Stem leathery, resembling a quill. H. Stem medullous, naked. Chap. II.

Species.

Intestina.

Ordo V. INFUSORIA. Animalia minima simpli- ciora.

+ Organis externis.

68. BRACHIONUS. Corpus testa tectum, apice cilia- tum. 69. VORTICELLA. Corpus nudum, apice ciliatum. 70. TRICHODA. Corpus altera parte crinitum. 71. CERCARIA. Corpus rotundatum caudatum. 72. LEUCOPHRA. Corpus undique ciliatum.

†† Organis externis nullis.

73. GONIUM. Corpus angulatum. 74. COLFODA. Corpus finuatum. 75. PARAMESIUM. Corpus oblongum. 76. CYCLIDIUM. Corpus orbiculare vel ovatum. 77. BURSARIA. Corpus cavum. 78. VIRBIO. Corpus elongatum. 79. ENCHELIS. Corpus cylindraceum. 80. BACILLARIA. Corpus ex trabeculis in varias formas accommodatis compositum: 81. VOLVOX. Corpus sphericum. 82. MONAS. Corpus punctiforme.

ORDER V. INFUSORIA. Animals extremely mi- nute and simple.

+ Furnished with external organs.

B. Body covered with a shell, and ciliate at the tip. V. Body naked, and ciliate at the tip. T. Body hairy on one side. C. Body rounded and furnished with a tail. L. Body everywhere ciliate.

†† Without external organs.

G. Body angular. C. Body finuate. P. Body oblong. C. Body orbicular or ovate. B. Body hollow. V. Body elongated. E. Body cylindraceous. B. Body composed of straight straw-like filaments, in position. V. Body spherical. M. Body a mere point.

CHAP. II. CLASSIFICATION AND NATURAL HISTORY OF THE SPECIES.

SECT. I.

ORDER I. INTESTINA.

LINNAEUS gave the name of intestina to this order, from the circumstances of their living in concealed situa- tions; while others have denominated these worms in- testinal, from the ordinary habitation of many of them; viz. the intestines of other animals. As all of this or- der, however, do not live in these situations, the term is not strictly proper. It would perhaps be better to follow the example of Goeze, and arrange all the para- sitical worms in a separate order.

The most esteemed works on the subject of the intes- tina, are those of Pallas, De infestis viventibus intra vi- ventia; Muller, Historia vermium; Bloch, a work in German, afterwards translated into French; Goeze, who also published in German; Werner, Lamarck, La- treille; and two papers by our countrymen Mr Carlisle and Dr Hooper, which will be mentioned particularly hereafter.

Anatomists have not examined a sufficient number of these animals, to render an account of their general structure either accurate or interesting; but we shall take occasion to detail that of some of the more impor- tant species under their proper heads.

There is nothing in the economy of animals more obscure, than the origin of those intestinal worms which inhabit within other animals. Were they found to live out of these animals, it might easily be supposed that their ovula were taken with the food and drink into the body, and there gradually evolved into perfect worms.

Vol. X. Part I.

This, however, is not the case; most of them do not seem capable of living for any length of time in any other situation than within a living animal body, which appears to be the proper place for their growth and re- sidence. We might hence be led to another supposi- tion; that these worms are really formed from the mat- ter within the intestines, which had previously no re- gular organization, were not this idea widely different from all analogy in the production of animals, where there has been any proper opportunity of examining this production. The origin, therefore, of these ani- mals is a subject of much obscurity. Dr Baillie is of opinion, that when the whole evidence in support of both hypotheses is compared, the grounds for believing that, in some orders of animals, equivocal generation takes place, appear stronger than those for a contrary opinion.

Merid. Anatomy, chap. viii.

I. ASCARIS.

Body round, elastic, and tapering towards each extremi- ty; head furnished with three vehicles; tail either lobulate or obtuse; intestines spiral, white, and pel- lucid.

This tribe is one of the most numerous of these para- sitical worms, late discoveries having discovered species of it in a great variety of animals, quadrupeds, birds, fishes, insects, and even worms themselves. The most important are those which inhabit the human intestines; and to these we shall chiefly confine our attention, avail- ing ourselves of the excellent paper on these worms in- ferred by Dr Hooper in the fifth volume of the Memoirs of the Medical Society of London.

U u A. Infesting A. Ingesting Man.

Head slightly curved inwards, with a transverse contraction beneath it; mouth triangular. Fig. 1.

When full grown, they are from 12 to 15 inches in length; and in circumference equal to that of a goose quill.

The head is to be distinguished from the tail by a small contraction, very obvious when the worm is lying down; it is trilobated, having three vehicles and a triangular aperture, between which is the mouth. These three globose papillae are joined together at their bases, and are of the same colour as the rest of the worm.

The tail may be known from the head by its very acute termination, close to which is a large orifice, the extremity of the intestinal canal, which may determine the anus.

The body is that part between the two extremities, forming nearly the whole of the worm; it puts on a rugose appearance, and has a line very apparent running on each side, and extending from one end to the other. Between these two lines are two other lines running parallel with the former, scarcely visible. Near the middle of the body (rather towards the head) is a circular depression of about one fourth of an inch in extent, in which is a very small punctiform aperture. This depressed band is irregular in its appearance, when the body of the worm is distended, although it would appear to be wanting when collapsed, in which state it mostly escapes from the intestines.

They generally infest the small intestines, and of these more frequently the course of the jejunum and ileum. Sometimes they are known to ascend through the duodenum into the stomach, and are frequently seen to creep out at the mouth and nostrils; it happens but rarely that they descend into the large intestine, and only after the exhibition of worm medicines, or from other causes, which increase the peristaltic motion. They have also been detected, after death, in the common biliary duct, and instances are related where they have remained a considerable time in the gall bladder.

They are in general very numerous, and Dr Hooper relates an instance of above two hundred having been voided in the course of a week. Thirty or forty is a very common number, but now and then only one is found.

When recently excluded they are transparent, and appear as if they had been sucking water tinged with blood; this colour, however, soon disappears, and they become at length of a light and opaque yellow.

When voided they are in general very feeble and soon die, but when suddenly expelled, they sometimes appear very lively. Their motion is serpentine, but is not produced by the diminution of the length of the animal by contraction. The head is sent forward by the worm curling itself into circles, and suddenly extending itself with considerable force to some distance.

This species does not, like most of this order appear to be hermaphrodite, but the male and female are said to be distinct worms.

The covering or external membrane of the worm, which may be considered as the cuticle, is very strong, elastic, thin, smooth, and transparent; and easily separates from the parts beneath, if the worm be macerated a few days after death in water.

Under the cuticle lies the cutis, or true skin, which is considerably thicker than the former, and retains the marks of the muscles which it covers. It is also very strong, elastic, and transparent.

When the cutis is removed, the muscles, observable through the skin of the worm, present themselves. They do not entirely surround the worm, as from their appearance one would be induced to believe; but are, in fact, two distinct orders acting in opposition to each other; for the two longitudinal lines, which extend from one extremity of the worm to the other, are each of them composed of two distinct tendons, separable from one another. These tendons serve for the attachment of the circular muscles, which cover the worm from the head to the tail.

Upon removing carefully the semilunar muscles from the head to the depressed band, a number of minute vehicles are to be seen (by means of a glass) filled with a submucous fluid, which flows out upon puncturing them.

This cellular or parenchymatous apparatus, closely embraces the intestinal tube from the head to the depressed band; but from thence to the tail, there is merely a fibrous connecting substance, similar to what is generally called cellular membrane.

When the muscles are removed from the depressed band to the tail of the worm, an extremely delicate membrane presents itself, analogous to the peritoneum, for it embraces the abdominal viscera, and lines the cavity of the abdomen.

The cavity of the abdomen extends from the depressed band near the middle of the worm to the tail; it is mostly distended with a transparent fluid, and contains the intestinal tube and an apparatus supposed to be subservient to generation, which constitute the abdominal viscera.

The intestinal canal begins at the obtuse extremity or head, from the external triangular mouth situated between the three globose papillae, and is continued for a small space downwards (nearly half an inch) in a parallel form. Having attained the size of a crow quill, it passes in a straight direction (and gradually enlarges as it advances) through the whole length of the worm, to within the eighth part of an inch, where it becomes suddenly narrower, and terminates in the anus.

This canal is generally filled with a greenish-coloured fluid, of the confluence of mucus, and not very unlike to the meconium of infants.

If a portion of this tube be macerated for a few days in water, it exhibits distinct coats, the external of which is a production of the peritoneum; it is externally covered with filaments, which connect it to the abdominal parietes. The second viscus is considered by some as peculiar only to the female worm, but all agree, that it is for the purpose of generation. It begins near the middle of the worm, where the cavity of the abdomen commences, by a slender tube, which is continued from the punctiform aperture, situated in the depressed band between the two longitudinal lines. This tube, which is termed the vagina, soon becomes much larger, when it commences uterus, and divaricates into two large crura, which, for the space of four or five inches, are continued of an uniform diameter; they then on a sudden, Species. Intestina.

fudden, become much diminished in size, and appear like opake threads, embracing in every direction, the intestinal tube. These are by Werner considered as the fallopian tubes.

This convoluted apparatus is composed of very fine transparent membranes. It is never found empty, but is always distended with an opaque fluid, in which are a number of globular bodies, or ovula, containing young worms.

It has been supposed by some that these worms are viviparous; an opinion which seems to have arisen from mistaking the nature of an appearance that not unfrequently takes place; viz. a protrusion of the gyrated apparatus above described, the filaments of which look very much like young worms. A convincing proof of their being oviparous is afforded by the fact, that ovula, differing in no respect from those found in the uterus of the worm, have been found in the mucus of the intestines by which they are surrounded.

This species was long considered as the same with the common earth worm, to be mentioned presently. There are, however, many striking differences, which will be enumerated under that species.

Head subulate; skin at the sides of the body very finely wrinkled. Vid. fig. 3. and 4.

When full grown, it is about half an inch long, and in thickness resembles a fine piece of thread. The body forms about a third part of the length of the animal, beginning immediately from the head, and terminating in the tail, which is distinguished by its gradually diminishing. The worm is wrinkled, annular, and pellucid. The tail terminates in a fine point; and when viewed with a magnifying glass, appears furnished with wrinkles or thick firm rings, and at its beginning there is a small opening through which the excrements pass.

They are most commonly situated in the rectum, and are continually passing away. They are frequently met with in the cæcum and colon, and have been found in the stomach and small intestines, lying hid between their coats. They are generally in considerable numbers, especially in the rectum of children; when they inhabit other parts, their numbers are less considerable, though above an hundred have been known to be vomited from the stomach of a young woman in the course of a day.

Their natural colour is a pale yellow, though they are often observed of a pale green, or occasionally of a brown colour.

When the animal wishes to shift his place, he first moves his head, which he turns in every direction, sometimes in a circle, at others so as to form the figure eight; most commonly its tail appears fixed, while it turns its body sometimes to one side, and sometimes to another. They are extremely lively, and have been seen to bury themselves almost instantaneously in the soft tissues of children, when they are exposed to the air. By some they are said to jump from one place to another; and hence the name *ascariides*, or leaping worms, from *araneus*, to leap.

These animals are certainly male and female, and, unlike the last species, they are viviparous.

The integuments of this species resemble those of the last, but there do not appear to be any longitudinal bands on its surface. The cavity, in which the bowels are situated, begins at a very small distance from the head, and terminates at the commencement of the tail.

The only visceræ in the male worm are the gullet, the stomach, and the intestine. The gullet begins at the mouth, from which it gradually enlarges for a small space, till it terminates in the stomach. This is a roundish bag, forming with the gullet, an organ shaped like the pestle of a mortar. The intestinal canal is continued, more or less contracted or dilated, till it terminates in the anus. The contents of this canal are always of a dark brown colour.

Besides these organs, the female has an apparatus appropriated to generation. It begins by a slender tube leading from a very small opening that is situated nearly in the middle of the body of the worm. It soon becomes much larger, embraces the intestinal tube in every direction, and fills up the cavity of the worm. It is nearly of an equal size throughout, and when viewed with a microscope, it appears like a bladder distended with living worms.

Various mammalia are also infested with ascarides, of which the following species are enumerated.

A. vespertilionis, found in the long-eared bat; pho-mammali-ca, found in several species of seal; bifida, inhabiting um. the phoca Greenlandica, or Greenland seal; * canis, in the intestines of the dog; visceralis, in the kidneys of the same animal; lupi, in the wolf; vulpis, in the fox; leonis, found under the skin of the lion; tigridis, in the intestines of the tiger; fells and cati, both found in the cat; martis, in the intestines of the martin; bronchialis, in the lungs, and renalis, in the kidneys of the same animal; mephitidis, in the viscera of the skunk; gulonis, in the glutton; talpe, in the mole; muris, in the mouse; hirci, in the goat; vituli, in the lungs of cattle; * equi, in the horse; suis, in the intestines of swine, and apri, in the lungs of the boar.

The following species are found in birds.

A. Aquilae, in the eagle; albicillæ, in the intestines of avium; the falco albicilla; buteonis, in the buzzard; milvi, in the kite; sibbutonis, in the hobby; hermaphrodita, in the pithecus ætivus; cornicis, of the crow; coracis, in the skin about the throat of the roller; cygni, in the swan; anatis, in the wild duck; fuligulae, in the tufted duck; * carbonis, in the corvorum; * pelicanis, in the flag; lari, in the gull; ciconiae, in the stork; tardi, and the papillofa, in the intestines of the buzzard; gallopavium, in the turkey; galli, in young fowls; gallinae, in the hen; phasianis, in the phasianus pictus; tetraonis, in the grouse; columbae, in the house pigeon; alaudae, in the lark; sturni, in the starling, and turdi, in the thrush.

The following infest reptiles.

A. testudinis, the round tortoise; lacertæ, the newt; reptilium, bufonis, the toad; pulmonalis, the lungs of the toad; rubetrae, also in the toad and matter jack; trachealis, in the lungs of the toad; range and intestinalis, found in the intestines of frogs; dyspnoeas, in the lungs of frogs, so as to impede their respiration; and insons, also found in the lungs of frogs, but without impeding their breathing.

The following infest fish.

Anguillæ, found in the eel; * marina, in herrings; piscium, bleaks, and other fish; blemni, in the blenny; rhombi, in the pearl; percæ, in the perch; globicola, found in the three-spined stickle-back; * lacustris, in the stickle-back and pike; siluri, in the silurus glans; fationis, in the trout; truttae, in the trout; marcesse, in the latino marina; acus, in the common pike; haecis, in the herring; argentinus, in the argentine or silver fish; gobiensis, in the liver of the gudgeon; raja, in the tail-ray; squale, in the shark; and lophii, in the gullet of the frog fish.

One species, viz. A. lumbrici, is found in lumbrici, between the skin and humours, though it is so small, as to be visible only by means of a microscope.

The species of ascaris already known, amount to about eighty.

"We are not to suppose (says Mr Bingley) that these worms are created for the purpose of producing disease in the animals they inhabit, but rather, that nature has directed that no situation should be vacant, where the work of multiplying the species of living creatures could be carried on. By thus allowing them to exist within each other, the sphere of increase is considerably enlarged. There is, however, little doubt that worms, and more especially the tape worms (to be perfectly described), do sometimes produce diseases in the body they inhabit; but we are at the same time very certain, that worms do exist abundantly in many animals without at all disturbing their functions, or annoying them in the slightest degree; and we ought to consider all the creatures rather as the concomitants than the causes of disease."

2. Trichuris.

Body round, elastic, and variously twisted; head much thicker than the other part, furnished with a slender, extensible proboscis; tail long, capillary, and tapering to a fine point.

Body above slightly crenate, smooth beneath, and very finely streaked on the fore part. Vid. fig. 5. and 6.

The body, when full grown, equals in breadth the one-fifteenth of an inch. In length the whole worm measures nearly two inches, two-thirds of which are tail, hence the French call it le ver à queue.

The large extremity of the trichuris is the head, out of which proceeds a kind of proboscis, not always visible, for the animal has the power of ejecting and drawing within itself this instrument at pleasure.

The body may be said to begin at the basis of the proboscis; it is the thickest part of the worm, and the most so at the extremity, where the proboscis is received. It gradually diminishes in size as it proceeds, and forms about one-third of its length.

The tail commences where the body terminates. It is twice as long as the body, and appears like a fine hair, gradually becoming smaller, and at length terminates in a very fine point.

Upwards of twenty have been seen in some faeces of a child six years old, and according to the account of Blumenbach, they are, in general, in considerable number.

Wrisberg, Blumenbach, and others, have found these worms in the intestineum rectum, in the inferior part of the ileum, and also in the jejunum, mixed with their pulchaceous contents. They have seldom, if ever, been seen after death, but in the cæcum. In colour it resembles the ascaris vermicularis.

Goeze has given a drawing of a female trichuris, and says it has no proboscis, which he supposes to be the male organ of generation; but as there is no material difference in the visceræ of particular individuals, Dr Hooper is inclined to doubt the fact.

This curious and singular animal is supplied, like the foregoing genus, with annular muscles, cutis, and cuticle.

The proboscis, which is undoubtedly the head of the worm, appears to be formed of a transparent substance, and contains a canal which is continued through the pulpy or funnel-like portion to the stomach and intestine.

The stomach and intestine are formed by a long canal, which proceeds in a direct line from the head to the very extremity of the worm. It is largest at its beginning, and continues of the same size throughout the body of the animal; and when arrived at the place where the tail commences, it suddenly becomes considerably less in diameter, and terminates in the anus.

The remaining viscus, or ovarium, is a convoluted canal, similar to that of the female vermicular ascaris, but is seldom found embracing the intestinal tube. The contents of this canal are ovula and a limpid fluid. There have seldom been seen any young worms.

Besides the above species, five others have been de-mammali-scribed; viz. T. equi, found in the intestines of the um horde; april, in the boar; muris, in the mouse; vulpis, in the fox; and lacerta, in the lacerta apus.

3. Filaria.

Body round, filiform, equal, and quite smooth; mouth dilated, with a roundish concave lip.

The most important species of this genus is the F. medinensis, or guinea worm. Gmelin has arranged it or gui-the animal as a filaria, though Linnæus makes it a spe-nea worm. Species of gordius, in which he is followed by Brugiere and Barbut. Mr Bingley, in his Animal Biography, chooses to consider it as the same with the furia infer- nalis of Linnæus, a species to be mentioned by and bye. The French call it dragonneau, and the older medical writers, dracunculus. It is characterized by having the body entirely of a pale yellow colour. It inhabits both the Indies and the coast of Guinea, and is said commonly to make its appearance in the morning dew. It enters the feet and other exposed parts of the slaves, and occasions very troublesome symptoms.

It attacks most parts of the body; but is generally confined to the lower extremities, particularly to the feet and ankles. The disease is more painful and dangerous when seated in parts thinly covered with flesh, such as near the joints, tendons, and ligaments, and less so in muscular parts. It is always difficult to extract the worm from the ankles, tarsus, and metatarsus, and sometimes impossible from the toes. The consequences frequently are, tedious suppurations, contractions of the tendons, diseased joints, and gangrene. When pulled, the worm often excites a pain which it is not easy to describe, and which, in these parts, is extremely exquisite. It seems to attach itself to the nerves, ligaments, and tendons, and when pulled even with the slightest force, excites excruciating pain. The track of the animal appears to be for the most part con- Species, fined to the cellular membrane, and probably seldom extends deeper, or penetrates into the interstices of the mucilages.

The disease produced by this animal is a species of inflammation, which sometimes is very troublesome, and now and then is said to terminate in mortification. The worm sometimes appears at first like a hair, and becomes thicker as it is drawn from below the skin. It generally has a sharp point, and is otherwise all of the same thickness. It may sometimes be felt below the skin, like the string of a violin. Various causes are assigned for the generation of this worm, but in the countries where it is usually found, it is thought to be generated by drinking impure water. It is more probable that it infatuates itself from without.

The method commonly employed for extracting this animal is, to search for its extremity in the inflamed part, where there is usually an ulcer, and this is to be drawn out gently, and wrapt round a piece of linen rag, when the pulling is continued very gently till the worm makes so much resistance that there is great danger of breaking it, an accident which is said to be attended with very bad consequences, as the remaining part of the worm becomes more irritating, and produces a more violent degree of inflammation. When no more will easily come away, the part already extracted, rolled round the rag, is left to dry, the part covered from the air, and the operation is repeated occasionally till the whole worm is withdrawn.

Four species of filaria are found in some of the mammalia, viz. F. equi, in the cellular membrane of the horse; leonis, in the lion; martis in the martin; and leporis, in the hare.

Five infest birds, viz. F. falconis, the hawk; strigis, the owl; cornicis, the crow; ciconiae, the stork; and gallinae, the intestines of poultry.

The following infest perfect insects, viz.

F. scarabaei, the scarabaeus semitaurus; filphae, in the filpha obfusca; carabi, in the carabus; grylli, in the cricket, and monoculi, in the monoculus apus.

Thirteen are found in the larva of various species of insects.

There are about 28 species of this genus distinguished in the Systema Naturæ.

4. Uncinaria.

Body filiform, elastic, the fore part obscurely tuberculate, with membranaceous angular lips; tail of the female ending in a fine point, of the male armed with two culpitate hooks inclosed in a pellucid vehicle.

Of this genus there are only two species; viz. melis, found in the intestines of the badgers; and vulpis, in those of the fox.

5. Scolex.

Body gelatinous, variouly shaped, broadish on the fore part and pointed behind; sometimes linear and long, sometimes wrinkled and short, round, flexuous, or depressed; the head protrusive and retractile.

This genus also contains two species; viz. pleurohectidis, and lophii, both found in several species of fish.

6. Ligula.

Body linear, equal, long; the fore part obtuse; the hind part acute, with an impressed dorsal future.

There are two species of this genus, viz. intestinalis and abdominalis, infesting several varieties of fish.

7. Linguatula.

Body depressed, oblong; mouth placed before, surrounded with four papillæ.

Of this genus there is only one species, viz. ferrata, found in the lungs of the hare.

8. Strongylus.

Body round, long, pellucid, glabrous; the fore part globular, truncate, with a circular aperture fringed at the margin; the hind part of the female entire and pointed, of the male dilated into loose, distant, pellucid membranes.

There are two species, viz. equinus, found in great numbers in the intestines of the horse, and ovinus in those of sheep.

9. Echinorhynchus.

Body round; proboscis cylindrical, retractile, and crowned with hooked pricks.

This is a very numerous genus, and is found in a great variety of animals, generally in their intestines, to which they are found very firmly fixed, often remaining on the same spot during the whole life of the animal. They are commonly gregarious, and are to be distinguished from the taenia, to be presently described, by their having the body round, and destitute of joints.

Four species infest the mammalia, viz. E. phocaæ, found in great numbers in the intestines of the harp and lium, rough seal, so as sometimes nearly to devour them; tubifer, in the stomach of the harp seal; gigas, in swine, especially those kept in styæ; and baleneæ, in the intestines of the whale.

14 infest birds, viz. E. buteonis, the buzzard; scopis, avium, in the strix scopo; aluconis, in the strix aluco; strigis, in the tawny owl; pici, in various species of picus borealis, in the cider duck; bochadis, in the common duck; anatis, in the velvet duck; mergi, in the mergus minutus; alceæ, in the auk; ardeæ, and gazeæ, in the ardea alba, or white heron; vanillæ, in the lapwing, and merulæ, in the blackbird and tree sparrow.

Two infest reptiles, viz. E. raneæ, the frog; and salamandæ, the salamander.

28 infest fish; viz. E. anguillæ, the eel; xiphia, the sword-fish; candidus, found in several species of fish; lincolatus, in the cod; longicollis, in the torp; pleurohectis, in the turbot; attenuatus, in the flounder; annulatus, in the father-lasher, torp, and bream; platefoideæ, in the pleuronectes platefoideæ; percæ, in the perch; cerneæ, in the ruffe; cobites, in the bearded loach; salmonis, in the salmon; fublobatus, and quadriforis, found also in salmon; truttae, in the trout; murenae,

Species. Intestina.

murenae, in the falso murenas; luci, in the pike; argentine, in the argentine; alofa, in the thad; barbi, in the barbel; carpionis, in the carp; idbari, in the cyprius idbarus; affinis, in the roach; rutili, also found in the roach, but seldom; brame, in the bream; lophii, in the frog-fish, and sturionis, in the sturgeon. There are in all about 48 species.

Hæruca.

Body round, the fore part two-necked, and surrounded with a single row of prickles; proboscis none.

There is only one species, viz. H. muris, found in the intestines of the mouse.

Cucullanus.

Body sharp, pointed behind, and obtuse before; mouth orbicular, with a striate hood.

There are eight species, three of which are found in various mammalia, viz. C. talpae, and ocreatus in the mole; and muris in the mouse.

One infects birds, viz.

C. buteonis, commonly found in the buzzard.

One, viz.

C. ranae, is found in the intestines of the frog.

Several varieties under the common name of lacustris, and two others, called alcaroides, and murinus, are found in various species of fish.

Caryophyllaeus.

Body round; mouth dilated and fringed.

There is only one species, called caryophyllaeus piscium, found in various species of fishes.

Fasciola.

Body flatfish, with an aperture or pore at the head, and generally another at a distance beneath, seldom a single one.

Cuvier remarks, that the body of the fasciola is extremely flat. They appear to be hermaphrodite, and are oviparous. They are found in almost every species of animals.

One is found in man, though rarely, viz. fasciola hominis.

Twelve in various species of the mammalia, viz. vulpis, in the intestines of the fox; putorii, in those of the polecat; melis, in those of the badger; vespertilionis, in the intestines of the long-eared bat; * hepatica, in the livers of sheep; boun, in those of cattle; porcorum, in the liver of swine; apri, in that of the boar; cervi, in that of deer; equi, in the liver of horses; and elaphi, in the stomach of the stag.

Of these, the most important is the fasciola hepatica, or fluke, which is so common in the liver of sheep, in which it is supposed to be the principal cause of the rot. — This species is about an inch long, broadest on the fore-part, which is furnished with a large mouth. It terminates in a tube; the back is marked with a row of about eight longitudinal furrows. It is generally found fixed by two points, one at one extremity, and another at about the middle of the abdomen. It bears some resemblance to the feed of the common gourd, whence it is often called the gourd worm.

The opinion of flukes being the cause of the rot, has been ably controverted by several writers, especially by Dr Harrison. On this subject, see the article Farifry, No. 526. This opinion is supposed to be corroborated by a circumstance related in the first volume of the Monthly Magazine, page 101. of a jelly-like substance being found among the grubs, in a pasture that was notorious for rotting sheep. This substance bore a striking resemblance to the flukes found in the liver of rotten sheep; but we are afterwards told, that having been walked into a ditch, and attended to daily, it was, in process of time transformed into a small snail, with an ash-coloured spiral shell. It is therefore probable that it was not flukes; and indeed there is no well authenticated instance of these animals having been found out of the bodies of sheep, except when it could be proved, that they had been vomited by those animals.

Nine species of fasciola are found in birds, viz.

F. bilis, in the gall duct of the eagle; butonis, in the buzzard; milvi and strigis, in the intestines of the kite; puflila, found in the thorax of the strix alba; anatis, in the duck; anferis, in the goose; gruis in the crane, and ardea, in the bittern.

Three species infest reptiles, viz.

F. salamandri, the salamander; ranae, the common frog, and uncinulata, the esculent frog.

21 inhabit various kinds of fish, viz.

F. Binodis, diticha, anguillae, scabra, eglefni, blen-piscium, nii, scorpi, platefex, lucioperce, percae, lugena, clavata, varica, eriocis, farionis, trutta, umblae, lucii, halecis, * bramae, jefis.

One, viz.

F. loliginis, inhabits the sepia loligo, or cuttle fish.

Tænia.

Body usually flat, and composed of numerous articulations; head with four orifices for suction, which are seated a little below the mouth; mouth terminal, continued by a short tube into two ventral canals, and generally crowned with a double series of retractile hooks.

The species of this genus, which are very numerous, are distributed into three sections, according to the situation which they inhabit in various animals, &c.

A. Found in other parts besides the intestines, and furnished with a vehicle behind.

The species of this section are commonly known to medical writers by the name of hydatids, from the bladders, of which they are chiefly composed, being filled with a watery fluid.

The following inhabit various species of mammalia; viñeralis T. viñeralis, piliform, inclosed in a vehicle, broad on or hydathore part, and pointed behind.—Found in the liver, lids, placenta, kidneys, fats containing dropical fluids, and other morbid tumours in man.

There is no gland in the human body in which hydatids are so frequently found as the liver, except the kidneys, where they are still more common. Hydatids of the liver are usually found in a cyst, which is frequently of considerable size, and is formed of very firm materials, Species materials, so as to give to the touch almost the feeling of cartilage. This cyst, when cut into, is obviously laminated, and is much thicker in one liver than another. In some livers, it is not thicker than a thimble, and in others, it is near a quarter of an inch in thickness. The laminae which compose it are formed of a white matter, and on the inside there is a lining of a pulpy substance, like the coagulable lymph. In a cyst may be found one hydatid, or a greater number of them. They lie loose in the cavity, swimming in a fluid; or some of them are attached to the side of the cyst. They consist of a round bag, which is composed of a white, semi-opaque, pulpy matter, and contain a fluid capable of coagulation. Although the common colour of hydatids be white, yet they are seen occasionally of a light amber. The bag of the hydatid consists of two laminae, and possesses a good deal of contractile power. In one hydatid, this coat or bag is much thicker and more opaque than in another, and even in the same hydatid different parts of it will often differ in thickness. On the inside of a hydatid, smaller ones are sometimes found, which are commonly not larger than the heads of pins, but sometimes they are even larger than a gooseberry. These are attached to the larger hydatid, either at scattered irregular distances, or so as to form small clutters; and they are also found floating loose in the liquor of the larger hydatids. Hydatids of the liver are often found unconnected with each other; but sometimes they have been said to inclose each other in a series, like pill-boxes. The most common situation of hydatids of the liver, is in its substance, and inclosed in a cyst; but they are occasionally attached to the outer surface of the liver, hanging from it, and occupying more or less of the general cavity of the abdomen.*

Another species called cellulosa, is found in the cellular membrane of man.

The following infect others of the mammalia, viz. T. finise, found in the diaphragm of the ape; vesperitionis, in the liver of the bat; vulpis in the fox; putorii, in the pole-cat; urin, in the bear; gulonis, in the glutton; hydatigena, in various species of rat; murina, in the liver of the mouse; cordata, in mice and hares; piliformis, in the liver of hares; utricularis, in the gravid uterus of the same animal; ferarum, in deers and antelopes; caprina, in the goat; ovilla, in the liver and omentum of sheep; cerebralis, within the skull of sheep, constituting the disease called flurdy or turn-sick; (see Farriery, No. 521.) vervecina, in the peritoneum of fat sheep; granulosa, in the liver of sheep; bovina, in cattle; apri, in the boar; globosa, chiefly found in the bowels of swine; and pinna, in the cellular substance of swine.

Two infect reptiles, viz. T. salamandri, the salamander; and serpentinum, in various serpents.

One viz. T. truttae, is found in the liver of the trout.

The origin and real nature of hydatids are not fully ascertained. There is no doubt at all, that the hydatids in the livers of sheep are animalcules; they have been often seen to move when taken out of the liver, and put into warm water; and they retain this power of motion for a good many hours after a sheep has been killed. The analogy is great between hydatids in the liver of a sheep, and in that of a human subject. In both they are contained in strong cysts, and in both they consist of the same white pulpy matter. There is undoubtedly some difference between them in simplicity of organization; the hydatid in the human liver being a simple, uniform bag, and the hydatid in that of the sheep having a neck and mouth appended to the bag. This difference need be no considerable objection to the opinion above stated. Life may be conceived to be attached to the most simple form of organization. In proof of this, hydatids have been found in the brains of sheep, resembling almost exactly those in the human liver, and which have been seen to move, and therefore are certainly known to be animalcules. The hydatids of the human liver indeed, have not, as far as we know, been found to move when taken out of the body and put into warm water; were this to have happened, no uncertainty would remain.

An excellent paper on the subject of hydatids, by Dr John Hunter, is contained in the Medical and Chirurgical Transactions.

B. Having no terminal vehicle, and found only in the intestines of other animals.

This section comprehends the teniae properly so called, or tape-worms, which are the most troublesome of all the species that inhabit the intestinal canal. Of these, the following two species that are confined to man, merit our particular attention.

Articulations long and narrow, with marginal mouths, folium, one on each joint, and generally alternate; ovaries arborescent. Vida fig. 7. and 8.

This species is frequently bred in the intestines of the inhabitants of Germany, and occasionally, but rarely, in those of the inhabitants of Great Britain. It consists of a great many distinct portions, which are connected together so as to assume a jointed appearance; these joints are commonly of a very white colour, but are occasionally brownish, which depends on a fluid of this colour that is found in their vessels. The worm is usually very long, extending often many yards, and seldom passes entire from the bowels. This circumstance has prevented the extremities of the tenia from being often seen.

Boerhaave mentions his having met with a tenia cells in length, and Pliny says he has seen them upwards of 30 feet long. According to Dr Hooper, the exact length depends upon the manner in which the death of the animal has been occasioned. If expelled by irritating medicines, it will not be so long by nearly one-half as if its death had been occasioned by emollients; as in the former instance it would be very much contracted, but in the latter very much relaxed.

The head of this tenia is somewhat of a square form with a narrowed projection forwards; in the middle of this projecting part, there is a distinct circular aperture around the edge of which grow curved-shaped processes. Near the angles of the square edge of the head, are situated four round projecting apertures at equal distances from each other; this head is placed upon a narrow jointed portion of the worm, of considerable length, and which gradually spreads itself into the broader joints, of which the body of the worm is composed.

The body of the tenia consists of thin, flat, pretty long joints, on one edge of which there is a projection, with a very obvious aperture. In the same worm some of these joints appear considerably longer than others; this probably depends on one joint being contracted, while another is relaxed. The apertures which we have just mentioned are generally placed on the edge of the contiguous joints; but this is not uniformly the case; they are sometimes placed on the same edges of two, or even several contiguous joints. When these joints are examined attentively, there are frequently seen, in each of them, vessels filled with a brownish fluid, and disposed in an arboreal form. Around the edges of each joint, there is also a distinct serpentine canal. The last joint of a tenia resembles very much a common joint rounded off at its extremity, and without any aperture.

The joints of this species are very easily separated from each other whilst the animal is alive. This separation is effected either by the peristaltic motion of the intestines, or perhaps spontaneously. Each joint thus detached from the mother worm, has the power of retaining, for a considerable time, its living principle, and is called, from its resemblance to the seed of the gourd, *vermis cucurbitinus*. This phenomenon has given rise to many warm disputes; several authors have denied their being portions of tenia, and have affirmed that they were distinct worms. The separated joints do not appear capable of retaining their situation for any length of time, but are soon forced down the intestinal tube, and at length creep out, or are expelled per anus. There are several cases faithfully recorded, where the persons, if their veracity can be depended upon, (and they had no interest in deceiving) have voided, during the time they were troubled with the worm, upwards of fifteen thousand.

This worm is not in general solitary, as is commonly supposed, for several of them have been seen coming away at the same time.

They are always found in the small intestines, commonly occupying their whole extent.

The motion of these worms is undulatory. The first joint towards the head contracts; the succeeding ones follow successively, and the worm is at length drawn considerably forwards, exactly in the same manner in which the earth-worm is seen to move, only considerably slower. By this means the food taken in at the mouth of the worm is very soon conveyed all along the alimentary canal, and may sometimes be seen moving along with considerable rapidity.

There can be very little doubt, that the tenia is hermaphrodite. The ova are observed to be vivipara, subservient to the propagation of the species, as it can be proved, that they give exit to the ovula.

Articulations short and broader than those of the last, with a mouth in the centre of each joint; ovaries fillate round the mouth.

It is composed of a head, a chain of articulations, and a tail formed of a round joint, as in the last species. The head is similar to that of the other species.

The joints are more uniform in their appearance than those of the tenia folium. They are considerably more broad than long, and their ova are not placed on the margin, but in the middle of the flattened surface, and only on one side. We have never seen them change their side, but have always observed them on the same side throughout the whole extent of the worm.

In every other respect the description of this species agrees with that above given of the other, except that the ovaria are in the form of a rose or star, hence they are called by some writers, *ovaria rostellata*, and others, *ligamenta rostellata*; and that the transverse canals by which there is in the other species a communication between the longitudinal canals are in this wanting.

The number of this species is uncertain, but there are seldom more than three or four.

Its length is commonly less than that of the last species, seldom exceeding five yards.

It is always situated in the small intestines, and it appears that it feeds on no other food than pure chyle.

It is for the most part of a darker hue than the former species, though they have been seen as white as milk.

This species is very seldom met with in this country, but is endemic in Switzerland and Ruffia, and very common in Germany and some other parts of Europe.

For a more particular account of the anatomical structure of teniae, we refer our readers to a paper by Mr Carlisle, in the second volume of the Lin. Trans. and Dr Hooper's paper in the fifth volume of the Memoirs of the Medical Society of London. For an account of the symptoms produced by these worms and the affections, and the method of treatment, see Worms, Medicine Index; and for the remedies employed in these cases, see Anthelmintics, Materia Medica Index.

The following species inhabit various mammalia, viz:

Cateniformis, of which there are seven varieties mammalia found in the dog, the wolf, the fox, the cat, the squirrel, red, and the dormouse; cucurbitina, in the dog; ferrata, in the dog and cat; maniliformis, in the cat; lineata, in the wild cat; mutteae, in the weasel, martin, and polecat; filamentosa, in the intestines of the mole; erinacei, in the hedge-hog; straminea, in the mus cricetus; magna and quadriloba, in the horse; and caprina, in the goat.

The following infect birds, viz:

Pithecus, in the pithecus brachyurus; cornicis, in the crow; serpentiformis, in crows, rooks, and magpies; caryocactus, in the nut-cracker; crateriformis, in the spotted wood-pecker; torqueta, in the duck; fecopacis and filum, in the woodcock; infundibuliformis, in the buzzard, ducks, and poultry; sturni, in the starling; paetris, in the sparrow; and hirundinis, in the martin swallow.

One, viz:

T. Nodulosus, infects various species of fish.

C Head unarmed with hooks.

Of this section the following infect the mammalia, mammalia viz:

Dentata, sometimes said to be found in mankind; phoca, in the great seal; baillaris, in the mole; pecinata, in the hare and rabbit; ovina, in sheep; equina in the horse; and suis, in the Ethiopian hog.

The following are found in birds, viz:

Globifera, in the buzzard, lanner, and thrush; perata, in the buzzard; flagellum, in the kite; candelabra, in the Aluco owl; crenata, in the spotted woodpecker; lanceolata, in the merganser and smew; fetigera, Species, Intestina.

Gera, and anseris, in the goose; anatis, in various species of duck; lavis, in the duck, &c.; cuneata, in various species; aleu, in the auk; torde, in the razor-bill; tarda, in the bustard; lineae in partridges; and maculata, in the red-wing.

One, viz.;

Batis, is found in the toad and salamander.

The following infest fish, viz.

Anguillae, in the cel; rugosa, in the cod; scorpii, in the armed bullhead; percæ, in the sea perch; erythrine, in the Norway perch; ceruæ, in the ruffe; folida and galeroetel in the stickle-back; fluri, in the silurus glanis; falmonis, in the salmon; freolichii, in the falmo wellmanni; rectangulum, in the barbel; torula, in the cyprinus jefes; and laticeps, in the bream.

Gmelin, in his edition of the Systema Naturæ, enumerates 86 species of the tænia.

Furia.

Body linear, equal, filiform, and ciliate on each side, with a single row of reflected prickles pressed close to the body.

There is only one species, viz. infernalis.

From the account given of this animal in the Syst. Nat., it appears to be a very formidable creature. It inhabits the extensive marshy plains of Bothnia; is about an inch long, and of a pale red or brown colour, generally with a black tip. It mounts up the edges and shrubs, and being driven by the wind through the air, enters through the skin of men and horses in such parts as are exposed and situated obliquely; leaving a black mark where it had entered. It first excites a sensation like the prick of a needle, which is followed by violent itching and acute pain. An inflammation and commonly gangrene is the consequence, attended with fever, faintings and delirium, and frequently terminating in a short time in death, unless the worm is speedily extracted, which is a work of considerable difficulty. The part where the worm entered is to be scarified, and anointed with oil of birch, or covered with a poultice of curds or cheese.

Gordius.

Body round, equal, filiform, and smooth. Body pale brown (or yellowish) with dark extremities. Water hair-worm.

This worm is about the thickness of a horse's hair, and when full grown, is ten or twelve inches in length. Its skin is somewhat gloomy, and of a pale yellowish white, except the head and tail, which are black. It is common in our fresh waters, and particularly in such where the bottom is composed of soft clay, through which it passes as a fish does through water.

Its popular name arose from the idea that it was produced from the hair of horses and other animals that were accidentally dropped into the water; an idea that is yet prevalent among the lower classes of people.

Its Linnaean name of gordius originated in the habit that it has of twisting itself into such peculiar contortions as to resemble a complicated Gordian knot. In this state it often continues for a considerable time, and then slowly disengaging itself, extends its body to the full length. Sometimes it moves in the water with a tolerable quick undulatory motion like that of a leech; and at other times its motions are the most slow and languid imaginable. When the water in which it swims happens to be dried up, it soon loses every appearance of life; the flabby body shrivels, and it may be kept in this state a considerable time. But whenever it is put into water its body soon reassumes its former appearance; in less than half an hour it begins to move, and in a few minutes more it is as active and lively as ever. How long it may be preserved in this dried state without losing its life, or how often it might admit of being revived, has not been ascertained. When kept in a vessel of water, it will sometimes appear motionless and as if dead for several hours, and afterwards will resume its vigour, and seem as healthy as before.

It is a very remarkable circumstance, that its bite, which it sometimes inflicts on being taken out of the water, has been known to produce the complaint called a whitlow. This is mentioned by Linnaeus as a popular opinion in Sweden, and it has since his time been confirmed by various other persons.

This gordius is sometimes found in the earth as well as in water, and particularly in gardens of a clayey soil, after rain.

Besides this species four others are enumerated, viz.

Argillaceus, filum, lacteus, and arenarius; but it is probable that the first of these, which is said to pierce through clay, to give passage to water, is merely a variety of the aquaticus.

Hirudo.

Body oblong, truncate at both ends, unarmed and cartilaginous, moving by dilating the head and tail, and contracting itself into an arch.

Elongated, of an olive black colour, with six yellow medicina-ferruginous lines above, and yellow spots below. Medici-lis-nal leech.—This species is generally two or three inches long, when lying in its natural state, though it is capable of very great dilatation. The body is composed of numerous annular wrinkles, which may be seen projecting, and by which the animal can expand or contract its body at pleasure. The head is smaller than the tail. This latter terminates in a circular mouth or sucker, which, when applied to any substance easily adheres; probably by the animal's drawing up the middle, and thereby exhausting the air below. By means of the tail it fattens itself with ease and security, while it extends the other parts of its body in any direction; and it is so firmly fixed, that it can move about without any danger of being carried away by the current. When the animal is desirous of changing its place, it extends its body forwards, fixes its head in the same manner as it did its tail, which latter it then loosens, draws up, and then fattens near its head, so as to form a fresh point from which to continue its movements.

Its head is furnished with three teeth, of a substance resembling cartilage, which are so situated as to converge when the animal bites, and to leave a triangular mark on the skin. These teeth are so strong that by means of them the animal can pierce the skin of an ox or a horse, as well as that of man; and through the holes which it forms, it sucks the blood. This appears to be done by contracting the muscles of its throat, so as to make the blood rush through the vacuum formed above the wound, into the stomach of the leech. This stomach is a kind of membranaceous skin, divided into small cells. If suffered to retain the blood which it has sucked, this is said to remain in the stomach of the animal, for months together, almost without coagulating, and to afford support to the animal during the whole of that time. It appears to pass off through the pores of the skin by transpiration, the matter fixing on the surface of the body, and afterwards coming off in small filaments. Mr Bingley affirms in proof of this, that if a leech be immersed in oil (where it will keep alive for several days), and afterwards put into water, a slough will be seen to loosen from its skin, exactly of the shape of the animal.

It is viviparous, and produces only one at a time, which is commonly in the month of July. It inhabits clear running waters, but may be kept for a considerable time in vessels partly filled with water, which should be changed occasionally, when it becomes putrid. In general, if the number of leeches kept together is not great, the water need not be changed oftener than once a month in winter, and once every fortnight in summer; and we have known instances where several leeches have, when neglected, lived for several months in the same water. If, however, the number be large, they frequently die, which is thought to be owing to their fighting and killing each other.

When leeches are to be applied for the purpose of extracting blood from any part of the body, the most lively, and those of moderate size, should be selected for that purpose; and they should be suffered to remain out of the water in a covered vessel for some time before they are applied. The best method of applying them is, to put them within a hollow glass tube, ground smooth at one end, open at both extremities, and bended so as to admit of its being applied to any part occasionally. The leech will commonly soon fix, but the skin to which it is to be applied should always be washed thoroughly clean, and should be freed from hair. If the animal is averse to fix, it may often be enticed to do so by rubbing the part of the skin with a little fresh cream, or new milk. When the leech has gorged itself with blood, it commonly drops off spontaneously; but if it should be too long in quitting its hold, it may be speedily made to do so by inserting a little salt, pepper, vinegar, or other acid substance, between the margin of its head and the skin. As a leech, after it has been used for drawing blood, will not, for a long time, suck again, if suffered to retain the blood it has drawn, various methods have been contrived to evacuate the blood. The common method is, to sprinkle a little salt upon its mouth, which commonly makes it disgorge a great quantity of blood; but we are not certain whether more animals are not killed in this way than by suffering the blood to remain. The most effectual, and we believe the safest method of making them disgorge the blood is, to lay hold of them by the tail, and strip them between the fingers, after which they should be put into clean water.

The best method of conveying leeches to a distance is, to put them into a strong, wide-mouthed glass bottle, and to put with them a piece of sponge thoroughly wetted with water, tying a piece of bladder pricked with holes over the mouth of the bottle.

It is said that leeches, when kept in bottles, will become very restless just before a change of weather is about to take place. This may be the case, but from many observations which we have made, we believe that they afford very uncertain presages of the state of the atmosphere.

Elongated, of an olive brown colour, with an ochre-yellow marginal band. Horse-leech.

This is larger than the former; its skin is smooth and glossy; its back of a darkish colour, and the belly of a yellowish green; its body is depressed. It inhabits stagnant waters. It is to be carefully distinguished from the former species, as it will not answer the purposes of surgery.

Besides these two species, the following are described in the Systema Naturae, viz.; indica, lineata, oculata, stagnalis, complanata, viridis, heteroclyta, geometra, telesata, marginata, grossa, hippoglossi, crenata, muricata, and branchiata. In all 17 species.

18. Lumbricus.

Body round, annulate; generally with an elevated, fleshy belt near the head, and commonly rough, with minute concealed prickles, placed longitudinally, and furnished with a lateral aperture.

There are 16 species of this genus, viz.; terrestris, marinus, vernicularis, variegatus, tubifex, lineatus, ciliatus, tubicola, echeirus, thallina, edulis, oxyurus, fragilis, armiger, corretus, labellaris.

Of these, the only one of which we shall make particular mention, is the terrestris, common earth-worm, or dew-worm. Body red, with eight rows of prickles.

This worm has neither bones, brains, eyes, nor feet. It has a number of breathing holes situated along its back, near each ring. Its heart is placed near the head, and may be observed to beat with a very distinct motion. The body is formed of small rings, furnished with a set of muscles that enable it to act in a sort of spiral direction; and by this means it is capable, in the most complete manner, of creeping on the earth, or penetrating into its substance. Mr Bingley explains the motion of these animals by that of a wire wound about a cylinder, where, when one end is drawn on and held fast, the other, upon being loosed, will immediately follow. These muscles enable the worm to contract or dilate its body with great force. The rings are each armed with small, stiff, sharp prickles, which the animal is able to open out or close upon its body; and from beneath the skin there is secreted a slimy matter, which, by lubricating the body, greatly facilitates its passage through the earth.

It is of consequence to point out the difference between this worm and the Acanthocephalus, or long-headed round worm of the human intestines, described at page 338, as they have been supposed to be merely varieties of the same animal. The common earth-worm has its extremities much blunter than those of the intestinal; coiled, its mouth consists of a small, longitudinal fissure, situated on the under surface of a small rounded head, there being no appearance of the three vehicles to evident in the acanthocephalus. On the under surface of the earth-worm there is a large semilunar fold of skin, into which the head retreats; but this is entirely wanting in the acanthocephalus; the anus of the earth-worm opens at the very extremity. Species. tremity of the tail, and [not as in the alcaris, at a considerable distance from the tail. The alcaris also wants the transverse rugae which are so strongly marked in the earth-worm, as well as the broad yellowish band by which the body of the latter is surrounded.

The internal structure of these two species of worms is also extremely different. In the earth-worm, there is a large and complete stomach, consisting of two cavities; and the intestinal canal in the latter is likewise larger, and more formed into sacculi than the alcaris. The parts subservient to generation in these two species of worms differ very much from each other; in the alcaris there is a distinction of sex, the parts of generation being different in the male and in the female; in the common earth-worm the organs of generation are the same in each individual, as this worm is hermaphrodite. The appearance, too, of the organs of generation, is extremely different at first sight in the one species of animal and the other. There is an oval mass situated at the anterior extremity of the earthworm, resembling a good deal the medullary matter of the brain.

Dew-worms, though in appearance a small and despicable link in the chain of nature, yet, if lost, might make a lamentable chasm. For, to say nothing of half the birds and some quadrupeds which are almost entirely supported by them, worms seem to be the great promoters of vegetation (which would proceed but ill without them) by boring, perforating, and loosening the soil, and rendering it pervious to rains and the fibres of plants, by drawing straws and stalks of leaves and twigs into it; and most of all, by throwing up such infinite numbers of lumps called worm-casts, which form a fine manure for grain and grass. Worms probably provide new soil for hills and slopes when the rain washes the earth away; and they affect slopes, probably to avoid being flooded.

Gardeners and farmers express their detestation of worms; the former, because they render their walks unsightly, and make them much work; and the latter, because they think worms eat their green corn. But these men would find, that the earth, without worms, would soon become cold, hard-bound, and void of fermentation, and consequently sterile; and besides, in favour of worms, it should be hinted that green corn, plants and flowers, are not so much injured by them as by many species of insects in their larva or grub-state, and by unnoticed myriads of those small shell-less snails called flugs, which silently and imperceptibly make amazing havoc in the field and garden.

19. SIPUNCULUS.

Body round and elongated; mouth cylindrical at the end, and narrower than the body; aperture at the side of the body warty.

There are two species; viz. S. * nudus and faccatus.

Body covered with a close skin, and globular at the lower end. Naked tube worm.—This animal is about eight inches long, and nearly of a conical figure from head to tail, having the base usually about nine lines, and the other extremity about four lines in diameter. The broader part of the body is the head, and is furnished with a mouth, in which there is a tube made of a strong membrane, and armed with three fleshy-pointed papillae, about the size of a grain of millet. This trunk is at one end every where connected with the rim of the mouth, but is loose at the other end. It may be extended to the length of an inch, or entirely withdrawn at the pleasure of the animal, probably for the purpose of seizing its food, and carrying it to its mouth. When the tube is out of the mouth, the papillae are on the outside, but they occupy the inside of the mouth when the tube is within. Hence the food laid hold of by the disengaged part of the trunk cannot escape; as the further the trunk is drawn back into the mouth, it is arrested by so many more papillae, which like prongs are ready to detain it. At the distance of an inch and a half from the mouth there is an oblong aperture, surrounded with a prominent lip, and situated transversely.

The whole body of this animal is of a fallow white, inclining to a clay colour, and is adorned with deep streaks; some of which are longitudinal, and others circular. Sometimes this animal will extend itself to almost the length of a foot, while at other times it contracts into a very small volume, by enlarging the narrower portion of its body near the point, which is spherical.

It inhabits deep seas, from which it is never cast on the shore, but it sometimes enters the fishermen's nets along with their fish.

Body covered with a loose skin, and rounded at the faccatus, lower end. Vid. fig. 9.

This animal differs little from the former, except in the loose skin in which the animal is enclosed as in a bag. It inhabits the American and Indian seas.

20. PLANARIA.

Body gelatinous, flatfish, with a double ventral pore; mouth terminal.

The animals comprehended under this genus nearly resemble the leeches, and like them live in fresh water. They are very numerous, but, as nothing remarkable is known respecting them, we shall merely enumerate their names.

A. Without eyes.

Stagnatus, nigra, brunea, ciliata, gulo, punctata, flaccida, rolea, angulata, rubra, viridis, operculata, subulata, quadrangularis, bicornis, grisea, fulva, viridata.

B. Having a single eye.

Glaucia, lineata, niellans.

C. Having two eyes.

Fuca, lactea, tonica, tentaculata, crenata, Lelluo, obscura, rostrata, atomata, cornuta, radiata, frigata, grossa, linearis, terrestris, tetragona, capitata, caudata, auriculata, filaris, lingua.

D. Having three eyes.

Gefferensis.

E. Having four eyes.

Marmorata, candida, truncata. F. Having more than four eyes.

Tremellaris.

There are in all forty-two species.

This Order comprehends twenty genera, and about 406 species.

SECT. II.

ORDER II. MOLLUSCA.

We have already, in the second part of the article ANATOMY, chap. viii., given a sufficient account of the general structure of the animals of this order, and of the several subdivisions of it, as given by Cuvier, to whose writings and those of La Marck, the lovers of natural history are chiefly indebted for the present state of our knowledge respecting these animals. Cuvier includes under the mollusca all those animals which inhabit shells, as well as those which are naked. The latter only can be considered here, and we shall chiefly confine ourselves to some of the more remarkable species.

21. ACTINIA.

Body oblong, cylindrical, fleshy, and contractile, fixed by the base; mouth terminal, expanfile, surrounded with numerous tentacula, and without any other aperture.

This genus comprehends most of those extraordinary animals which have been described under the title of animal flowers, sea-mary-golds, &c., an account of which has been already given under the article ANIMAL-Flower. We shall here therefore only enumerate the species, which are 23 in number; viz. rufa, * crassicornis, * plumosa, * anemonoides, judaica, * esteta, coccinea, undata, viduata, * truncata, nodosa, spectabilis, digitata, gigantea, alba, viridis, priapus, candida, bicornis, vulva, * caryophyllus, iris, ficella, puffila, * cereus, * bellis, * gemmacea, * melembryanthemum, sociata, alter, anemone, helianthus, * dianthus, calendula, doliolum, * maculata.

22. CLAVA.

Body fleshy, gregarious, club-shaped, and fixed by a round peduncle, having a single vertical aperture.

There is but one species; viz. parasitica; characterized by its having a whitish, pellucid peduncle, and an opaque red club that is covered with erect, conical, pellucid spines. It is found in the Baltic sea, upon sea weeds, shell-fish, and floating timber. It possesses the power of dilating and contracting the mouth.

23. PEDICELARIA.

Body soft, and seated on a rigid fixed peduncle, having a single aperture.

There are three species; viz. P. globifera, triphylla, and tridens, all which are found in the North seas, chiefly among the spines of echini.

24. MAMMARIA.

Body smooth, and without rays, having a single aperture.

There are three species; viz. M. mammilla, varia, Species, and globulus. Found also in the North seas and on the shores of Greenland.

25. ASCIDIA.

Body fixed, roundish, and appearing to issue from a sheath, having two apertures, generally placed near the upper extremity, one below the other.

There are about 35 species of Ascidia; viz. papillofa, gelatinosa, * intefinalis, quadridentata, * ruflca, echinata, mentula, venosa, prunum, conchilega, parallelogramma, virginea, canina, patula, alpina, leabra, orbicularis, corrugata, lepadiformis, complanata, tuberculum, villoa, clavata, pedunculata, * mammillaris, globularis, fusca, gelatina, crytallina, octodentata, patelliformis, pyura, aurantium, globularis, falciculata.

Of these we shall describe only two, the papillofa, and the intefinalis.

Body rough, and covered with scarlet tubercles.—papillofa.

This animal is generally about three inches long, and something less than two broad; its shape is oval. On the upper part it is furnished with two mammary protuberances, one of which is seated on the top of the body, and has an orifice in the form of a crois. The other is placed a little below the former, and has a triangular orifice opening transversely. The lips of either orifice are encompassed with several fæceous hairs, of a clay colour, and one line in length, but observing no regular order. The whole surface of the body is rough, being covered over with small knobs or oblong nipples of a scarlet colour. The extremity opposite to the organs, or the basis, is furnished with peduncles of various forms, by means of which this animal firmly adheres to rocks or other bodies, so that it cannot be forced from its situation without injuring the peduncles.

The skin, which is thick and hard like the hide of a quadruped, constitutes by far the greater part of the animal's bulk; and there is scarcely anything distinguishable within, except a small part that commences a little below the orifice of the upper papilla, from which it proceeds downwards, and is inserted into the lower orifice, having the appearance of an intestine. From the appearance of this organ, it is supposed that the upper orifice is the mouth, and the lower the anus. This species is not used for food, though some of them are said to be eatable.

Body elongated, membranaceous, smooth, and whitish, appearing like the intestines of a quadruped.—If nalis, the membrane of which nearly the whole of this animal's body consists, be divided longitudinally, there appears another membranaceous canal descending from the upper organ, almost to the base, where it bends back, and proceeds towards the lower organ, into which it is inserted. This canal is commonly filled with a blackish fluid. These organs are sometimes strongly contracted, and at others as much relaxed. They do not appear like those of the former species, to be able to draw in and throw out the water.

The animals belonging to this genus have the power of squirting out the water they receive, as if from a fountain; and it is probable that they derive their nourishment from the animalcula which the water contains.

26. SALPA. 26. *SALPA.*

Body long, floating, gelatinous, tubular, and open at each extremity, with an intestinal tube placed obliquely.

The outer covering of these animals has two openings, one very large, serving for the introduction of the water in which they live between their branchiae, and the other smaller, which appears to be the anus. They have no head or feet. They are found in all our seas. Many of the species are remarkable for the regularity which they observe in their mode of swimming. They are gregarious, and one always follows at the tail of another, in such a manner as to touch each other, and to form two lines, one above the other, each individual of the upper line being supported by two of the lower.

The species are arranged under two subdivisions.

A. Furnished with an appendage.

This section contains four species; viz. maxima, pinata, democratica, and mucronata.

B. Having no terminal appendage.

This section contains seven species; viz. punctata, confederata, fasciata, spho, africana, solitaria, and polyacra.

27. *DAGYSA.*

Body loose, floating, angular, tubular, and open at each extremity.

There is only one species of this genus; viz. notata, characterized as having the body marked at one end with a brown spot. It is about three inches long, and one thick, and is found in the sea on the coasts of Spain. These animals adhere to each other by their sides, and in other respects very nearly resemble those of the last genus.

28. *PTEROTRACHIA.*

Body detached, gelatinous, with a moveable fin at the abdomen or tail; eyes two, placed within the head.

There are four species; viz. coronata, hyalina, pulmonata, and aculeata.

29. *DERRIS.*

Body cylindrical, composed of articulations; mouth terminal, feelers two.

There is only one species; viz. *sanguinea*, which is found on the coast of Pembrokeshire.—This animal has a tapering body to a point behind, and is capable of great flexibility; it is covered with a transparent membranous coat, through which the internal parts are visible. The head is extended beyond the outer skin, and is less than the rest of the fore part of the body. The tentacula are white, and seated at the top of the head. The mouth consists of two lips, the upper one hooked and moveable, the lower one straight and fixed. It moves by an undulating motion of the whole body.

30. *LIMAX.*

Body oblong, creeping, with a fleshy kind of shield above, and a longitudinal flat disk beneath; aperture Limax placed on the right side within the shield; feelers four, situated above the mouth, with an eye at the tip of each of the larger ones.

This genus comprehends those animals which are commonly called flugs, or naked snails, which are well known to commit such ravages in our fields and gardens, especially in wet weather.

There are 15 species; viz. levis, *ater, albus, *rufus, *flavus, *maximus, hyalinus, *agreftis, cinctus, marginitatus, reticulatus, aureus, fulcus, tenellus, and *lanceolatus.

The most curious species of this genus seems to be *agreftis*, what has been called the spinning flug, which is a variety of the limax *agreftis*.—This animal is of a grayish white colour with a yellowish shield, and is commonly about three-fourths of an inch long. It inhabits woods and other shady places. The following account of it has been given by Mr Hoy, in the first volume of the Linnean Transactions.

About the year 1789, Mr Hoy observed, in a plantation of Scotch firs, something hanging from one of the branches, which, as it seemed uncommon, he approached, and found it to be this animal. It was hanging by a single line or thread attached to its tail. This was upwards, very fine; but near the animal it became thicker and broader, till at length it exactly corresponded with the tail. The flug was about four feet below the branch, and nearly at the same distance from the ground; which it gradually approached at the rate of an inch in about three minutes. This rate, though slow, is not so much so as might be expected, considering that the animal is not furnished with any particular receptacle, as in some insects, for the gelatinous liquid from which its filken lines are formed. The line by which it descended was drawn from the slimy exudation gradually secreted from the pores that covered its whole body. A great degree of exertion seemed necessary to produce a sufficient supply of the liquid, and to force this towards the tail. It alternately drew back its head, and turned it as far as possible, first to one side and then to the other, as if thereby to press its sides, and thus promote secretion. This motion of the head in an horizontal direction made the whole body turn round; by which the line that would otherwise remained somewhat flat became round. This motion also, in addition to the weight of the animal, tended, no doubt, materially to lengthen the line.

In addition to Mr Hoy's account, Dr Latham observes, that the secretion from which the thread is formed, does not come from the back or sides of the animal, but from its under part. That it did not proceed from any orifice in the tail was evident, for in some instances the animal was suspended by the tip, and in others from the side full one-eighth of an inch from the tip. The flow of the viscid secretion towards the tail appeared to be excited by an undulating motion of the belly, similar to that of crawling.

After these animals have spun for some time, their spinning power seems to be for a while lost, but in all all those on which experiments have been made, it has been recovered again by keeping them for a few hours among wet moss.

31. LAPYLSIA.

Body creeping, covered with reflected membranes, with a membranaceous shield on the back covering the lungs; aperture placed on the right side; vent above the extremity of the back; feelers four, resembling ears. Vid. fig. 10.

An animal of this genus has been called the sea-hare, a name which is derived from the ancients; and the animal to which it is given appears to have been known at a very early period, and perhaps on that account its history is obscured with many fabulous narrations.

Fisherfolk seem in all ages to have attributed some noxious properties to those marine animals which do not serve for the nourishment of man; and the writings of naturalists are still filled with the reports of these ignorant men respecting several productions of the sea, as the sea-nettle, star-fish, and in particular the sea-hare. These relations have been multiplied and prodigiously increased with respect to the marvellous, whenever the figure, the colour, or smell of the animal have anything extraordinary or forbidding in them, as is the case with the sea-hare. Hence we find a long list of noxious and afflicting properties attributed to this animal. Not only are its flesh, and the water in which it has been steeped, of a poisonous nature, but even its very aspect is deadly. A woman who would wish to conceal her pregnancy, cannot resist the sight of a female sea-hare, which produces nausea and vomiting, and finally miscarriage, unless a male of the same species, dried and salted, is given her to eat; for it is one of the superstitious ideas entertained by the common people in most countries, that every noxious species of animal carries within itself a remedy for the ill effects which it may occasion. It happens, indeed, unfortunately for the present story, that in the sea-hare there is no distinction of sex. If these animals in Italy (for the above stories are taken from Pliny) are so deadly to mankind, it is quite otherwise in the Indian seas; for there it is man who is such a deadly foe to the sea-hare, that he cannot take it alive, since it is destroyed by his very touch!

These ridiculous fables respecting an innocent animal, are still believed by many people, and others as ridiculous have been added to them. Mr Barbut relates that a sailor happening to take a lapylia in the Mediterranean, it gave him such instantaneous and excruciating pain as to cause an inflammation, and the poor man lost his arm! and so sensible are the fishermen of the poisonous quality of the mucus which oozes from its body, that they will not on any account touch it.

In an excellent memoir on the lapylia, contained in the 2d vol. of Annales de Museum National, Cuvier gives the following general description of the animals composing the genus.

They bear a considerable resemblance to the slugs; their body is oval, flattened below, so as to form a long and straight foot, and swelling out above; more or less pointed behind, and diminishing a little before, so as to form a sort of neck, that is susceptible of various degrees of elongation, and at whose extremity is situated the head.

The head is the only superior part that advances beyond the borders of the disc that forms the foot. The other borders of this disc are contracted, so as to form a kind of palliade, surrounding the sides and back part of the body. This fleshy wall is contracted and raised more or less, and is folded into numerous undulations at the pleasure of the animal, who can fold the one part over the other, or can cause them to separate, so as to give them all manner of shapes. Between the borders we perceive a part almost semicircular, attached only by the right side, entirely moveable like a fleshy cover, the border of which is flexible, and sometimes forms a sort of gutter, to conduct the water to the organs of breathing, which are in fact under this cover. At the posterior extremity of its attachment is the anus, and between the anterior extremity of the same attachment, and that which corresponds to the membranaceous border of the body on the right side, is a hole, through which are passed the eggs of the animal, and that peculiar liquor which has been regarded as poisonous. But besides this liquor, which is whitish, and is rarely voided, the animal produces another kind much more abundant, and of a very deep purple red.

The mouth is situated below the head lengthwise, and the anterior border of the head forms on each side a membranous production that is conical, compressed, capable of being more or less prolonged, and forms a tentaculum. Behind the head, further back, there is on each side another conical tentaculum, which the animal can elongate or shorten at pleasure, but which he cannot withdraw within the body, like the snail. The extremity of this is a little folded longitudinally into two parts, so as to resemble the external ear of a quadruped. Before the base of this organ is the eye, which seems nothing but a little black point.

The parts above described are common to all the lapyliae, but differ in the several species in proportion and colour.

In the last edition of the Systema Naturae, only two species of lapylia are mentioned; viz. depilans, which appears to be the original sea-hare mentioned by Pliny, and which owes its trivial name to the belief that the fetid liquor which it exudes is capable of taking off the hair from any part which it touches; and fasciata. Besides these, Cuvier enumerates and figures three others, viz. camelus, punctata, and alba.

32. DORIS.

Body creeping, oblong and flat beneath; placed below, on the fore-part; vent behind on the back, and surrounded by a fringe; feelers 2—4, seated on the upper part of the body in front, and retractile within their proper receptacles.

This genus is divided by Gmelin into two sections.

A. Having four tentacula.

Of this there are seven species; viz. fasciculata, minimata, radiata, pennata, peregrina, affinis, and * argo.

B. Having two tentacula.

Of this section there are 17 species; viz. * verrucosa, Species fa, clavigera, quadrilineata, papillofa, auriculata, laciniata, cervina, coronata, tetraqueta, * bilamellata, olivelata, muricata, pilofa, laevis, arboreifrons, frondosa, and stellata.

In a long and interesting memoir by Cuvier on the genus doris, printed in the 4th vol. of Annales de Muséum National, that celebrated naturalist shows that only seven of the species enumerated by Gmelin (viz. argo, stellata, bilamellata, laevis, olivelata, muricata, and pilofa), really belong to this genus, and that the rest should be arranged under other genera.

Cuvier admits thirteen species, six of them new; and distributes them into two sections.

a. Flat doris,

Comprehending ten species; viz. folia, scabra, maculofa, verrucosa, limbata, tuberculata, stellata, pilofa, tomentofa, and laevis.

b. Prismatic doris,

Three species; viz. lacera, atro-marginata, and pulchrola.

We regret that our limits will not permit us to translate the valuable observations contained in this memoir, to which we refer the reader for the description of the above species, and of their general anatomical structure.

One of the most remarkable of the species is the argo, or sea argus, which we shall here describe. The whole body of the argus is obliquely flat, or perpendicularly compressed; its thickness in the middle is six lines, whence growing gradually thinner, at the edge it is no more than half a line thick. It is three inches and five lines in length, and two inches broad. The back shines with a scarlet dye, and the belly is of an agreeable clay colour, and both are curiously marked with white and black spots. The whole substance of the body is coriaceous and solid, and if cut through the middle, appears everywhere tinged with a saffron colour. Round the circumference of the body it is pliant, whence, at the animal's pleasure, it is formed into various folds and plaiting. The head, which in all other animals is easily known by the peculiarity of its structure, in the argus is not determinable when its back is turned to the spectator, for the oval shape of the body, of nearly the same diameter throughout the circumference, makes no distinction of head. The tentacula too, which appear toward each extremity, are so much alike in this situation, as not to serve for distinguishing the head; but if the animal be turned, it will appear that the head is situated in that part from which the tapered tentacula rise. One half of these tentacula is white, and sunk into small round cavities, formed to the depth of two lines in the substance of the head. Their apex is prominent from the cavity, and is everywhere marked with black dots, which are supposed to be so many eyes, and afforded the reason for denominating this animal argus.

If the tentacula are touched, they are immediately withdrawn entirely within their cavities. On the upper part of the head is a mamillary prominence, situated near the belly, at about half an inch from the edge, and in the middle is seen a small oval aperture, which is the mouth of the argus.

One of the most remarkable parts of the animal, and that which distinguishes it from all others, remains to be described.

On that part of the back which is opposite to the head, four lines distant from the border, is an oval aperture eight lines in length, and five broad. From the middle of this hole arises a fleshy trunk of a whitish colour, four lines long, one and a half broad, which divides into two larger branches, the right hand one subdivided into eight, the left into six lesser branches, which at length end in small slender twigs. Besides these, another large branch arising from the middle of the first trunk, runs off towards the head. On every one of the branches and twigs there are many black spots discernible by the naked eye, which contribute not a little to the beauty of this blooming part; but whether those punctures were hollow, has not been ascertained, even with the assistance of the microscope; though they are probably so many open mouths of vessels and breathing points. While the argus remains in the sea-water, it keeps this wonderful assemblage of lungs expanded; when out of the water, and touched with the finger, it contracts it into the form of a crown; and if the handling and irritation be continued for any time, it conceals the lungs entirely within the oval aperture, which is also then contracted into a narrower compass. Being put again into salt water, the aperture soon enlarges, and the branches of the lungs concealed within gradually push out again, lengthen, and expand.

33. Tethis.

Body detached, rather oblong, fleshy, and without peduncles; mouth with a terminal cylindrical proboscis, under an expanded membrane or lip; apertures two, on the left side of the neck.

There are only two species; viz. leporina, and fimbrida, the latter of which is a very elegant looking animal, about six inches long, with a white body, having a fringed border, variegated with black and clay colour, and in some places glittering with gold coloured spots. It is found in the Adriatic.

34. Holothuria.

Body detached, cylindrical, thick, and open at the extremity; mouth surrounded by fleshy branched tentacula.

There are 23 species of this genus, viz. elegans, frondosa, phantapus, tremula, phyllalis, thalia, caudata, denudata, * pentactis, papillofa, spallanzani, priapus, squamata, penicillus, fulus, inherens, laevis, minuta, forcipata, zonaria, vittata, maxima, and impatiens.

Of these we shall describe the holothuria tremula, which has the following specific character.

Upper surface covered with numerous conical papillae; lower with cylindrical ones; tentacula fasciculate. (Vid. fig. 11.)—This species commonly measures eight inches in length when dead; but alive it extends itself to more than a foot, or contracts its body into a ball. Its figure is cylindrical, the diameter of which is every way equal to an inch and a few lines. The back of a dark brown, proudly bears a variety of fleshy pyramid-like nipples, of a dark colour likewise at their basis, but white at their apex. They are observed to be of two two different sizes; the larger occupy the length of the back, in number 14 on each side, at the distance of six lines from each other, when the holothuria is contracted; but the intervening space is fully eight lines when the animal is extended. Others, like these, are placed here and there promiscuously. The lips are scattered in like manner, without order, in every part of the back. Out of them all exude a whitish mucilage, serving to lubricate the body. Hence all these nipples seem to be so many glands furnished with an excretory duct, the aperture of which is so minute as not to be discoverable by the help of a common glass. That they are, moreover, provided with various muscles, follows from hence, that the holothuria can raise and obliterate them at pleasure. While the larger papillae are quite erect, their axis, and the diameter of their base, measures three lines. The belly, or part opposite to the back, in the holothuria, is of a pale brown, and set all over with cylindrical tentacula, in such numbers, that the head of a pin could scarcely find room between them. Their diameter is not much above a line, and their length is that of four lines. They are of a thinning whitening, except the extremity, which is of a dusky dark colour, and shaped like a socket. By the help of these tentacula, the holothuria fixes its body at the bottom of the sea, so as not to be easily removed by tempests, which would otherwise happen very frequently, as this animal dwells near the flores, where the water scarcely rises to the height of a fathom. Now, if it adheres to other bodies by means of its ventral tentacula, their point must necessarily have the form of a socket, as the cuttle-fish, sea-urchins, and star-fish have theirs shaped, by which they lay hold of any other body.

From this situation of the holothuria at the bottom of the sea, which it also retains when kept in a vessel filled with sea water, it must be evident to any one, that we have not groundlessly determined which was its back, and which its belly, which otherwise in a cylindrical body would have been a difficult task. But as all animals uniformly walk or rest upon their bellies, and the holothuria likewise has likewise that part of its body turned to the earth on which the cylindrical tentacula are to be seen, it is clear that part is the abdomen or belly of this animal. However, both the abdominal and dorsal tentacula are raised and obliterated at the animal's pleasure, from which it is reasonable to conclude, that they are furnished with elevating and depressing muscles, and particularly because all the foreaid tentacula disappear after the animal's death; and hence it farther appears, that many naturalists have given a representation of a dead holothuria, since they have assigned it no tentacula.*

35. TEREVELLA.

Body oblong, creeping, naked, often inclosed in a tube, furnished with lateral faucicles or tufts and branchiae; mouth placed before, furnished with lips, without teeth, and protruding a clavate proboscis; feelers numerous, ciliate, capillary, feated round the mouth.

There are 11 species, viz. cirrata, lapidaria, * conchilega, complanata, carunculata, rostrata, flavia, rubra, aphroditois, biconis, and stellata.

Of these the terebella lapidaria, or stone-piercer; cal-

led by the French Pinceau de Mer; the sea pencil, is species thus described by Barbut. "From the midst of the Mollusca, hairs issues the head of this small animal, supported by a long neck, and putting forth two small branching horns. The mouth, which is round, is armed with small teeth, like those of the echini marini, with which it masticates its food. The hairs are very fine, soft as silk, and form a tuft, from the middle of which issues the neck, and then its head. The body is shaped like that of a worm, is very long, and terminates at one end in a point, which very much resembles the stick end of a painting brush. The small head of our terebella appears underneath, drawn back as in the snail. It walks or crawls by the help of five small feet, placed on each side of the large part of its body, at the rising of the tuft of hairs, and close to each other."

36. TRITON.

Body oblong; mouth with an involute spiral proboscis, having 12 tentacula, 6 on each side, divided nearly to the base, the hind ones being cheliferous.

There is only one species, viz. littoreus, found on the shores of Italy.

37. SEPIA.

Body fleshy, receiving the breast in a sheath, having a tubular aperture at its base; arms 8, befit with numerous warts or suckers; and besides, in most species, 2 pedunculated tentacula; head short; eyes large; mouth resembling a parrot's beak. Cuttlefish.

Cuvier divides the genus sepia into two, which he calls seiche, comprehending most of the species enumerated by Linnaeus under lepia, and poulpe, comprising two species. The former have a face, with a kind of fin on each side, and they contain towards the back a peculiar body of a friable or cartilaginous substance, transparent in the living animal, which is placed within the flesh, without adhering to it; and proceeding from one side to the other without any articulation. The head is round, and provided with two large moveable eyes, the organ of vision of which is almost as perfect as that of the eyes of warm-blooded animals. The mouth is situated at the top of the head, and has two similar jaws, in form and substance resembling the beak of a parrot, and surrounded with eight conical tentacula, furnished with suckers, by means of which the animal fixes itself to the rocks or other substances, so firmly, that it is often easier to tear away one of these arms than to induce the animal to quit its hold. The two others are very long, and have no suckers except at their extremity. These last seem to serve the animal for anchors to hold by.

Just before the neck there is a sort of funnel, which closes up the entrance of a face, and seems to be the anus. These animals have internally a liver, a muscular gizzard, a coecum, and a short intestinal canal. The circulation in these animals is carried on by very singular organs; there is a heart placed at the bottom of the face, by which the blood is distributed to every part of the body, by means of arteries, and to which it is returned by veins, through a large vena cava, which divides itself for the purpose of conveying the blood to two other hearts, one on each side, which distribute it to the gills, from whence it is passed to the first heart.

The female produces eggs that are assembled together in the form of a bunch of grapes.

These animals, when they perceive the approach of danger, emit a quantity of inky fluid, furnished by a particular vessel, and by thus obscuring the water, render their escape more easy, while from the bitterness of this liquid their foe is induced to give over the pursuit. There seems little doubt that the opinion of Swammerdam, that this liquor furnishes the Indian or China ink, is just; for if this ink be dissolved in water, in any considerable quantity, it very soon acquires a very high degree of putridity, which seems to prove that it is formed of some animal substance; and none seems better calculated for the purpose than this black liquor.

The second genus of Cuvier differs from the sepia, properly so called, in wanting the solid bony substance in the back, and the two long arms; but the eight tentacles are much longer in the individuals of this genus than in those of the sepia.

The male cuttle-fish always accompanies the female; and when he is attacked, he braves every danger, and will attempt her rescue at the hazard of his own life; but as soon as the female observes her partner to be wounded, she immediately makes off. When dragged out of the water, these animals are said to utter a sound like the grunting of a hog.

The hard substance, or bone as it is called, in the back of the cuttle-fish, when dried and powdered, is employed to form moulds, in which silversmiths cast their small articles, such as spoons, rings, &c.; and it also forms that useful article of stationary called pounce.

In the Systema Naturae there are described eight species of sepia, viz. * octopus, * officinalis, unguiculata, hexapus, * media, * loligo, * sepia, and tunicata.

Of these, the officinalis was in great esteem among the ancients as an article of food, and is still used as such by the Italians.

The sepia octopus, or eight-armed cuttle-fish, which inhabits the seas of warm climates, is a most formidable animal, being sometimes of such a size as to measure 12 feet across its centre, and to have each of its arms between 40 and 50 feet long. It is said that he will sometimes throw these arms over a boat or canoe, which he would infallibly drag to the bottom, with those who are in it, did not the Indians, who are aware of this danger, carry with them a hatchet to cut off the arms.

38. CLIO.

Body naked, free, and floating, furnished with a fin on each side; head distinct, and having gills at the surface of the fins.

The above character of clio is that of Cuvier, who has written an able account of this and two other genera of his new order of mollusca, which he calls pteropoda, or mollusca pinnae, in the 4th vol. of Ann. de Mus. Nat.

Gmelin enumerates six species of clio, viz. caudata, pyramidata, retusa, borealis, helicina, and limacina.

39. ONCHIDIUM.

Body oblong, creeping, flat beneath; mouth placed before; feelers two, situated above the mouth; arms two, at the sides of the head; vent behind, and placed beneath.

There are two species, viz. typhoe, which is described by Dr. Buchanan in the 5th vol. of the Linnaean Transactions; and peronii, described by Cuvier in a late number of the Ann. de Mus. Nat.

40. LOBARIA.

Body lobate, convex above, flat below.

There is only one species, viz. quadriloba, characterized as having a tail with four lobes. It is found in the north seas.

41. LERNÆA.

Body oblong, somewhat cylindrical, naked; tentacula or arms, two or three on each side and round, by which it affixes itself; ovaries two, projecting like tails from the lower extremity.

There are 15 species, viz. branchialis, * cyprinacea, * salmoncea, * afellina, * huchonis, clavata, uncata, gobina, radiata, nodosa, cornuta, pectoralis, lota, cyclopterina, and pinnarum.

42. APHRODITA.

Body creeping, oblong, covered with scales, and furnished with numerous brittle fasciculate feet, on each side; mouth terminal, cylindrical, retractile; feelers two, fetaceous, annulate; eyes four.

There are 9 species, viz. * aculeata, * scabra, * squamata, imbricata, plana, * lepidota; cirrofa, violacea, and longa.

Of these we shall describe the first, the aculeate aphrodite, by some called the sea mouse. It is of an oval form, grows to the length of between four and five inches; the belly is covered with a naked skin and somewhat prominent in the middle; its substance is somewhat firm. It is clothed with hairy filaments, which are short on the middle of the back, but longer at the sides; they are all somewhat rigid and firm; those on the back stand erect, like the quills of a porcupine; those on the sides lie flat, and are of a great variety of colours; a beautiful blue and lively green are very distinct in them, but a golden yellow seems the most predominant colour: on the back they are of a darker colour, and in many places of a grayish brown. It dwells in the European ocean, and lives upon shell-fish. It has 32 fasciculated projectors, resembling feet, on each side.

43. AMPHITRITE.

Body projecting from a tube and annulate; peduncles or feet small, numerous; feelers two, approximate, feathered; eyes none.

There are seven species, viz. reniformis, penicillus, ventilabrum, Species. ventilabrum, auricoma, cristata, chrysocephala, and Mollusca.

44. Spiro.

Body projecting from a tube, jointed, and furnished with dorsal fibres; peduncles rough, with bristles, and placed towards the back; feelers two, long, simple; eyes two, oblong.

There are two species, viz. feticornis and filicornis.

63 Nereis.

46. NEREIS.

Body long, creeping, with numerous lateral peduncles on each side; feelers simple, rarely none; eyes two or four, rarely none.

The species are 29 in number, and are divided into three sections.

A. Mouth furnished with a claw;

Containing vericolor, * nodiluca, fimbriata, armillaris, mollis, * delagica, tubicola, norwegica, pinnata, corniculata, pufilla, incifa, and aphroditoidea.

B. Mouth furnished with a proboscis;

Containing * cerulea, * viridis, maculata, crassa, stellifera, punctata, alba, flavo, longa, priscimica, bifrons, ceca, ebranchiata, lamelligera, and ciliata.

C. Mouth furnished with a tube;

Containing one species, viz. prolifera.

One of the most remarkable of these species is the nodiluca, of which we shall here give a short account.

Body blue green, with 23 segments, so small as to be scarcely visible to the naked eye.—This is one of those phosphorescent animals that illuminate the ocean in the dark. Their numbers and wonderful agility, added to their shining quality, do not a little contribute to these illuminations of the sea; for myriads of these animalcula are contained in a small cup of sea water. Innumerable quantities of them lodge in the cavities of the scales of fishes; and to them, probably, the fishes owe their noctilucent quality. "I have observed with great attention (says Barbus) a fish just caught out of the sea, whose body was almost covered with them; and have examined them in the dark: they twist and curl themselves with amazing agility, but soon retire out of our contracted sight; probably their glittering dazzling the eye, and their extreme minuteness eluding our researches. It is to be observed, that when the unctuous moisture which covers the scales of fishes is exhausted by the air, these animals are not to be seen, nor are the fishes then noctilucent, that matter being perhaps their nourishment when living, as they themselves afford food to many marine animals. They do not shine in the day-time, because the solar rays are too powerful for their light, however aggregate, or immense their number."

47. Naïs.

Body creeping, long, linear, depressed, and pellucid; peduncles, with small bristles on each side; no tentacula; eyes two or none.

There are 10 species, viz. vermicularis, * serpentina, * proboficidae, elinguis, * digitata, barbata, ceca, litoralis, marina, and quadriculipidata.

48. Physophora.

Body gelatinous, pendent from an aerial vehicle, with gelatinous feilie members at the sides; numerous tentacula beneath.

There are three species, viz. hydrostacta, rosea, and filiformis.

49. Medusa.

Body gelatinous, orbicular, and generally flat underneath; mouth central, beneath.

These animals have been denominated sea nettles, from the opinion that the larger species, when touched, excite a tingling sensation, and slight redness of the skin. They are supposed to form the chief food of the cetaceous fish; and many of them shine with great brilliancy in the water. The form of their body, while at rest, is that of the segment of a sphere, of which the convex surface is smooth, and the flat part provided with several tentacula. The body is transparent, and so gelatinous, that it is reduced almost to nothing, by evaporation, when left dry upon the shore. Several coloured lines may be seen within; but there is nothing which gives marks of a circulation going on. The lines, indeed, towards the borders are more numerous, but they seem to be appendages of the alimentary cavity. These animals swim very well, and appear to perform that motion by rendering their body alternately more or less convex; and thus striking the water. When left upon the shore, they lie motionless, and look like large flat cakes of jelly.

The species are distributed into two sections.

A. Body with ciliated ribs.

This contains four species, viz. infundibulum, pileus, cucumis, and ovum.

B. Body smooth.

This contains 40 species, viz. porpita, * cruciata, hylocella, * aquorea, * aurita, capillata, * pilaevis, marufupialis, hemispherica, pelagica, nodiluca, * fusca, * purpura, * tuberculata, * undulata, * lunulata, nuda, velelia, spirans, pulmo, tyrrhena, tubercularis, utricularis, caravella, umbella, dimorpha, campanula, digitata, frondosa, tetrastyla, octotyla, andromeda, corona, persea, cephea, proboficidalis, mollicina, pileata, crucigera, and unguiculata.

50. Lucernaria.

Body gelatinous, wrinkled, branched; mouth placed beneath.

There are three species, viz. quadricornis, phrygia, and auricula.

51. Asterias.

Body depressed, covered with a coriaceous crust; muriate, with tentacula, and grooved below; mouth central, and five-rayed. These animals, which are usually called *flor-fish*, or *sea-larts*, constitute one of the most numerous genera of the mollusca. They are very curious in their forms, but are almost all radiated, as stars are usually painted; and some of them, from the minuteness of their rays, make a very beautiful appearance.

By the coriaceous crust, with which they are covered, they are defended from the attacks of the smaller animals, that inhabit the seas in which they reside. Each of the rays has a great number of short, soft, and fleshy tubes, that serve for tentacula, and seem not only designed for taking prey, and aiding the motion of the animal; but also for enabling it to cling to the rocks, and thus resist the force of the waters. These tentacula have been found to exceed 1500 in a single animal; they are situated on the lower surface, and when the animal is laid on its back, they may be seen to be pushed out and withdrawn like the horns of snails. The rays enable them to swim, but they move very slowly. These rays are very brittle, and are easily broken off; but when this happens, their power of reproduction is so great, that they are speedily renewed. The mouth is armed with bony teeth, for breaking the shells of the small fish on which they feed; and from the mouth a canal proceeds through each of the rays, becoming narrower as it approaches the tip.

For preserving these animals, Mr Barbut advises that they be drowned in brandy or other spirits, taking care to keep the rays all the time extended. Then it is easy to draw out the entrails by the mouth with a pair of forceps; and after this is done, the animal may be dried.

There are 45 species distinguished, according to their circumference is more or less divided.

A. Lunate,

Comprehending four species, viz. nobilis, pulvillus, militaris, and luna.

B. Stellate,

Comprising 20 species, viz. papoosa, spongiosa, rubens, sepolita, endeca, minuta, glacialis, clathrata, echinitis, recticulata, phrygiana, nodosa, violacea, sanguinolenta, perforata, araneica, equetris, leavigata, membranacea, granularis.

C. Radiate,

Comprising 20 species, viz. rosea, pertusa, ophiura, aculeata, ciliaris, sphærolata, pentaphylla, varia, aculearis, haftata, filia, nigra, tenella, pettinata, multiradiata, caput medusa, euryali, aligates, nigrita, tricolor, and fragilis.

Many of these are extremely beautiful; but one of the most showy is the caput medusa, or arborecent flor-fish.

Having five rays, each subdivided, dichotomous; rays and disk granulate; mouth depressed (Vid. fig. 12.). —This extremely singular species is occasionally met with in most seas; but it is not very common. It has five equidistant, thick, jointed rays, proceeding from the centre; and each of them is divided into two other smaller, and each of these is again subdivided in a similar manner; and this subdivision is carried, in the most beautiful and regular gradation, to a vast extent, so that the extreme ramifications sometimes amount to several thousands. Mr Bingley speaks of a specimen that was three feet across, and had 512 extremities to each ray, making in all 2560. By this curious structure, the animal becomes, as it were, a living net, and is capable of entangling such creatures as are designed for its prey, by the sudden contraction of these numerous ramifications, by the intricacy of which they are prevented from escaping.

The colour of the living animal is a reddish or deep carnation; but when dead it is more of a gray colour. To preserve this curious animal whole and undamaged for cabinets, it should be taken far out at sea, and the fishermen should be careful not to break off any of the limbs, and to keep it as still as possible. It should be dried in the shade in some open place, as in the sun it is apt to melt away, and if too much in the shade, to become putrid.

This species is so valuable, that the fishermen at the Cape get from six to ten rix-dollars for a specimen.

51. Echinus.

Body roundish, covered with a bony crust, and generally furnished with moveable spines; mouth placed beneath, and commonly five-valved.

The animals of this genus are called *sea urchins* or *sea hedgehogs*, from the spines which grow on their external covering; they are also called *sea eggs*, probably from many of them being eatable. They are all inhabitants of the seas; and are so nearly alike in character, that a description of one species will serve to illustrate the whole family.

There are no less than 109 species, which are subdivided as follows.

A. Vent vertical, and all the tentacula simple.

a. Globular or hemispherical,

Containing 37 species, viz. *eculentus, sphæra, droebachienis, miliaris, basteri, haemisphericus, angulosus, excavatus, globulus, sphæroides, gratilla, lixula, faxatilis, fenestratus, subangularis, ovarius, diadema, calamaris, araneiformis, stellatus, radiatus, circinatus, cidaris, mamillatus, lucunis, atratus, coronatus, alterzans, afflatus, fardicus, lamneus, variegatus, pufualtus, granulatus, tessellatus, botryoides, and torcumaticus.

b. Shaped somewhat like a shield;

Four species, viz. *sinuatus, semiglobosus, quinquibiatus, and conoideus.

B. Having the vent beneath and no tentacula at the mouth.

a. Base circular, with the vent in the circumference,

Containing five species, viz. alba-gabrus, depressus, vulgaris, quadrifaciatus, and sexfaciatus.

b. Base exactly circular;

One species, viz. subuculus.

c. Base oval;

Three species, viz. cycloformus, semilunaris, and seniformis.

Y y 2

d. Base d. Base oval and acute; vent opposite the mouth;

Six species, viz. * scutatus, ovatus, * pustulosus, quadriradiatus, minor, and dubius.

e. Base irregular, with five expanded petal-shaped marks on the surface.

1. Margin with angular finuofities; Two species, viz. rofaceus and attus.

2. Ovate; margin entire; Two species, viz. oviformis and orbiculatus.

f. Flat on both sides, with petal-shaped avenues; mouth central, flat, and toothed; crown with four pores.

1. Having a finuated margin and perforated surface; Seven species, viz. biforis, pentaporus, hexaporus, emarginatus, auritus, inauritus, and tetraporus.

2. Having a finuated margin and entire surface; Five species, viz. * laganum, subrotundus, reticulatus, orbicularis, and gorallatus.

3. Having a toothed margin; Three species, viz. decadastylus, octadastylus, orbiculus.

g. With ten avenues on the crown; rays straight, biporous, and flellate; mouth and vent near each other in the middle of the base;

13 species, viz. nucleus, centralis, ervum, craniolaris, turcicus, vicia, ovulum, lathyrus, equinus, minus, falca, inaequalis, raninus, and butonius.

C. Vent lateral, with pencilled tentacula at the mouth.

a. Circular; mouth central, vent square; One species, viz. placenta.

b. Heart-shaped, with the crown grooved; Two species, viz. cor anguinum and lacunosus.

c. Heart-shaped, with the crown not grooved; Eight species, viz. radiatus, purpureus, pusillus, complanatus, * subglobulus, ananchitis, bicordatus, and carinatus.

c. Ovate, with grooved avenues; One species, viz. spatagus.

d. Ovate, with the avenues not grooved; Eight species, viz. brissoides, teres, oliva, amygdala, ovalis, pyriformis, lapifcaneri, and patellaris.

Many of the above have hitherto been found only in a fossile state.

Subglobular, with 10 avenues of pores; and the intermediate spines covered with small tubercles, supporting the spines. fig. 13.—This animal, which lodges in cavities of rocks, just within low water mark, on most of the British coasts, is nearly of a globular shape, having its shell marked into ten partitions or divisions, not much unlike those of an orange. The mouth is situated in the lower part, and armed with five strong and sharpened teeth. The stomach and intestines which are of considerable length, are disposed in a somewhat circular form; and the whole body is supported entirely by a set of upright bones or columns.

On the right side of the shell is a prodigious number of sharp moveable spines, of a dull white and greenish colour, curiously articulated, like ball and socket, with tubercles on the surface, and connected by strong filaments to the skin or epidermis, with which the shell is covered. The spines are the instruments by which the animal conveys itself at pleasure from one place to another; and by means of these it is enabled to move at the bottom of the water with great swiftness. It generally employs those about the mouth for this purpose, keeping that opening downwards; but it is also affected to have the power of moving forwards, by turning on itself like a wheel. When anything alarms these animals, they immediately move all their spines towards it, and wait an attack, as an army of pikemen would with their weapons. The number of muscles, fibres, and other apparatus necessary to the proper management of these must be very great, and are exceedingly wonderful. So tenacious are the sea-urchins of the vital principle, that on opening one of them, it is no uncommon circumstance to observe the several parts of the broken shell, move off in different directions.

Between the spines, and disposed in a continued longitudinal series on the several divisions or regions of the shell, are an infinite number of very small knobs, communicating with an equal number of tentacula placed above them. These are the instruments by which the creature fixes itself to any object, and stops its motion. They are possessed of a very high degree of contractile power, and are furnished at the extremities with an expanible part, which may be supposed to operate as a sphincter, or as the tail of a leech, in fastening the animal securely to rocks and other substances to which they choose to adhere.

The shell of this animal, when deprived of the spines, which easily fall off in dying, is of a pale reddish tinge, and the tubercles on which the spines are fixed, appear like so many pearly protuberances on the surface.

At Marteilles, and in some other towns on the continent, this species is exposed for sale in the markets, as oysters are with us, and is eaten boiled like an egg. It forms an article of food among the lower classes on the sea coasts of many parts of this country, but does not seem to have made its way to the tables of the great.

This order of Mollusca contains 32 genera, and about 433 species.

Order IV. ZOO PHYTA.

The creatures ranked under this order seem to hold a middle rank between animals and vegetables. Most of them are, like the latter, fixed by a root to a certain spot, from which they never move, and where they sprout and grow; many of them propagate, like plants, by buds, or flips; and some of them appear only to be entitled to rank as animal bodies by their possessing a degree of irritability a little superior to the sensitive plant. Few of them enjoy the faculty of locomotion, though the agility with which they seize their prey and the instinct which directs them in search of it, shew them to be really animal bodies. The coral reefs that surround many islands, particularly those in the Indian Archipelago, and round New Holland, are formed by various tribes of these animals, especially by those of the five first genera.

M. Peron observed, that the animals form these corals with such rapidity, that enormous masses of them very speedily appear, where there was scarcely any mark of such reefs before.

The principal works that treat of the Zoophyta are those of Ellis, Solander, Pallas, and Dr Shaw's "Naturalist's Miscellany".

53. Tubipora.

Animal probably a nervous; coral, consisting of erect, hollow, cylindrical, parallel, aggregate tubes.

There are 10 species, viz. mucifera, catenulata, * ferruginea, falciculata, ramofa, pennata, penicillata, flabellaria, stellata, and frutes.

54. Madrepora.

Animal resembling a medusa; coral with lamellate star-shaped cavities.

There are 118 species, which are distributed into five subdivisions, viz.

A. Composed of a single star,

Containing six species, viz. * verrucaria, turbinata, * porpita, fungitis, patella, and cyathus.

B. With numerous separate stars, and continued numerous gills.

14 species, viz. pileus, cristata, lactuca, ficoides, acrofa, lichen, agaricites, elephantatus, crullacea, incrufans, exefa, filograna, natans, and anthophyllum.

C. With numerous united stars.

There are 15 species, viz. labyrinthisca, sinuosa, meandrites, areola, abdita, phrygia, repanda, ambigua, daedalia, gyrofa, clivofa, cerebrum, involuta, implicata, and cochlea.

D. Aggregate undivided, having distinct stars, and porous, tuberculous, prominent undulations.

There are 56 species, viz. favoia, cavata, bulliris, ananas, hyades, fiderea, galaxea, pleiades, papillofa, radiata, latelobra, polygonia, arenofa, intertincta, spongiosa, foliofa, porculata, stellulata, astrottes, flottata, nodulofa, acropora, cavernofa, punctata, calycularis, truncata, stellaris, organum, divergens, * muflacis, denticulata, favoelata, retepora, rotulofa, cepitofa, flexuosa, fasciculata, peclinata, rotularis, tubularis, mamillaris, patelloides, globularis, telum, perforata, vermicularis, * arachnoides, undulata, folida, monile, dedalia, monostrata, contignatio, criftata, rus, and cupidata.

E. Branched, having distinct stars, and porous tuberculous undulations.

There are 27 species, viz. porites, digitata, damicornis, verrucosa, muricata, fafligata, ramea, oculta, virginea, rosea, hintella, limulata, botryoides, granofa, proliferata, feriata, cactus, corymbosa, gammacens, problematica, spuria, infundibuliformis, angulofa, difcoides, chalcidicum, concamerata, and rofacea.

55. Millepora.

Animal an hydra or polype; coral mostly branched, and covered with cylindrical, turbinate pores.

There are 34 species, viz. alcicornis, caerulea, alpera, folida, truncata, miniaeae, * cervicornis, * klenckei, pumila, comprefa, * lichenoides, violacea, tubulifera, * facialis, * foliacea, zeylanica, forniculosa, crutulenta, erofa, reticulata, * celluloa, clathrata, reticulum, spongites, coriacea, calcarea, * polymorpha, decussata, * alga, * pumicola, * tubulofa, pinnata, * liliacea, and cardunculus.

56. Cellepora.

Animal an hydra or polype; coral somewhat membranaceous, and composed of round cells.

There are eight species viz. ramulosa, spongites, * pumicosa, verrucosa, ciliata, hyalina, nitida, and annulata.

57. Isis.

Animal growing in the form of a plant; stem stony and jointed; the joints longitudinally streaked, united by horny junctures, and covered with a soft, porous cellular flesh or bark; the mouths of which are beset with oviparous polypes.

There are six species, viz. hippuris, dichotoma, ochracea, * entrocha, * alteria, and coccinea.

58. Antipathes.

Animal growing in the form of a plant; stem expanded at the base, horny within, and beset with small spines; externally covered with a gelatinous flesh, beset with numerous polypes bearing tubercles.

There are 13 species, viz. spiralis, ulex, subpinnata, myriophylla, allopecuroides, cupreus, oricaecea, dichotoma, clathrata, flabellum, pennacea, ericoides, and feniculacea.

59. Gorgonia.

Animal growing in the form of a plant; leathery, corky, woody, horny, or bony; composed of glairy or stony fibres; streaked, tapering, dilated at the base, covered with a cellular flesh or bark, and becoming spongy and friable when dry; mouths covering the surface of the flesh and polype-bearing.

There are 41 species, viz. lepadifera, verticillaris, * placomus, mollis, succinia, americana, exferta, patula, ceratophyta, juncea, flammea, umbraculum, purpurea, faflappo, palma, radicata, suberofa, coralloides, elongata, scirpea, fetacea, viminalis, muricata, * verrucosa, antipathes, * anceps, nobilis, crassa, pinnata, fanguinolenta, violacea, fetofa, petechizans, peclinata, abietina, calyculata, briareus, ventalina, reticulum, clathrus, and * flabellum.

60. Alcyonium.

Animal generally growing in the form of a plant; stem fixed, fleety, gelatinous, spongy or leathery, and beset with stellate cells bearing polypes. There are 28 species, viz. arboreum, exos, * digitatum, schlofferi, lyncurium, * burfa, cydonium, * ficus, gelatinosum, manus diaboli, * arenolum, botryoides, mafa, cranium, rubrum, mammillofum, ocellatum, tuberosum, gorgonoides, abeflum, albumen, papilliferum, * conglomeratum, * afacidoides, synovium, vermiculare, stellatum, and corniculatum.

61. Spongia.

Animal fixed, flexible, torpid, of various forms, composed either of reticulate fibres, or masses of small spines interwoven together, and clothed with a gelatinous flesh, full of small mouths on its surface by which it absorbs and rejects water.

There are 49 species, viz. ventilabrum, flabelliformis, infundibuliformis, fittularis, aculeata, tubulofa, * cornata, ciliata, cancellata, rubra, nigra, officinalis, * oculata, muricata, nodosa, * tentoformia, bacillaris, dichotoma, * stipula, * crista, * palmata, prolifer, * potrycides, * panicea, fulva, tubularia, fibrillofa, taficulata, baifa, lichenoides, papillaris, cavernosa, finuola, frondosa, agaricina, tupa, membranofa, compressa, penicillum, coaliata, plana, cruciata, oliformis, mauda, ficiformis, * lacustris, fluviatilis, friabilis, and canalicum.

The sponges consist of a ramified mass of capillary tubes, that were long supposed to be the production of a species of worms, which are often found within their cavities; an idea, however, which is now nearly exploded. Others have imagined them to be only vegetables; but that they are possessed of animality, appears evident from the circumstance of their pores alternately contracting and dilating, and from their even shrinking in some degree from the touch, when examined in their native situations. Their structure probably enables them to absorb nourishment from the surrounding fluid.

These animals are certainly the most torpid of all the zoophytes. The individuals differ very much from each other, both in form and structure. Some of them, as the common sponge, are of no determinate figure; but others are cup-shaped, tubular, &c.

Irregularly formed, porous, rough, lobed, and woolly.—The officinal sponge is elastic, and very full of holes; it grows into irregular lobes of a woolly consistence, and generally adheres, by a very broad base, to the rocks. It is chiefly found about the islands in the Mediterranean, where it forms a considerable article of commerce. A variety of small marine animals pierce and gnaw into its irregular winding cavities. These appear on the outside, by large holes raised higher than the rest. When it is cut perpendicularly, the interior parts are seen to consist of small tubes, which divide into branches as they appear on the surface. These tubes, which are composed of reticulated fibres, extend themselves every way, by this means increasing the surface of the sponge, and ending at the outside in an infinite number of small circular holes, which are the proper mouths of the animal. Each of these holes is surrounded by a few erect pointed fibres, that appear as if woven in the form of little spines. These tubes, with their ramifications, in the living state of the sponge, are clothed with a gelatinous substance, properly called the flesh of the animal. When the sponge is first taken it has a strong fishy smell, and the fishermen take great care in making it perfectly clean, in order to prevent its growing putrid.

62. Flustra, Sea Mat-Weed, or Horn-Wrack.

Animal a polype, proceeding from porous cells; stem fixed, foliaceous, membranaceous, composed of numerous rows of cells, united together, and woven like a mat.

There are about 18 species, viz. * foliacea, * truncata, * pilosa, * chartacea, * carbacea, bombycina, verticillata, * dentata, * bullata, tomentosa, denticulata, tubulofa, hispida, frondiculofa, papyracea, hirta, * membranacea, and lineata.

63. Tubularia.

Stem tubular, simple or branched, fixed by the base; animal proceeding from the end of the tube, and having its head crested with tentacula.

There are 26 species, viz. magnifica, cornucopiae, * indivisa, * ramosa, ramea, * filulofa, fragilis, * multifidae, papyracea, penicillus, acetabulum, splachnea, * coryna, * affinis, fabricia, longicornis, multicornis, repens, * campanulata, * reptans, fultana, stellaris, simplex, * pallanzani, membranacea, * and flabelliformis.

Of these, by far the largest, and probably the most beautiful species, is the magnifica, which is thus characterized by Dr Shaw.

With a simple whitish tube, and very numerous tentacula, variegated with red and white. (Vide fig. 14.)

It is found in various parts of the coast of Jamaica, adhering to the rocks. It is very shy, and on being approached, instantly recedes within its elastic tube, which on a farther alarm also retires into the rock, and specimens can be procured only by breaking off such parts of the stone as contained them. These being put into tubs of sea-water, may be kept for months in perfect preservation.

64. Corallina.

Animal growing in the form of a plant; stem fixed, with calcareous subdivided branches, mostly jointed.

There are 38 species, viz. tridens, opuntia, monile, infracta, tuna, nodulofa, * squamata, loricata, palmata, * elongata, subulata, granifera, * officinalis, pennata, * rubens, * crista, * spermophoros, * corniculata, fragillima, fruticulofa, indurata, lichenoides, rugosa, marginata, cylindrica, oblongata, obtusa, lapideiceps, barbata, rofarium, culpidae, tribulus, flabellum, conglutinata, phoenix, peniculum, penicillum, and teretris.

65. Sertularia.

Animal growing in the form of a plant, stem branched, producing polypes from cup-shaped denticles or minute cells.

There are 77 species, which are distributed into two sections.

A. Stem horny, tubular, fixed by the base, beset with cup-shaped denticles, and furnished with vesicles or ovaries containing polypes, eggs, or the living young.

* Rosacea, * pumila, * operculata, * tamarica, * abietina, Species etina, nigra, fusifascens, obsoleta, pinus, cupressoides, Zoophyta, cupreolina, argentea, rugosa, helecina, theja, myriophyllum, hypoides, speciosa, fulcata, pluma, echinata, antennina, verticillata, gelatinola, volubilis, syringa, culcata, putulofa, frutefascens, pinnataer, pennatula, filicina, quadridentata, spicata, evanflis, muricata, fecundaria, milieniflora, racemosa, uva, lindigera, geniculata, dichotoma, spinola, pinnata, fetacea, polygonias, pennaria, lichenatum, cedrina, imbricata, purpurea, articulata, filicina, and fruticae.

B. Stem cryfaceous, resembling stone, and composed of rows of cells; no vesicles, but instead of them small globules. Cellularia.

* Burfaria, loriculata, fastigiata, ovicularia, ne-retina, feropula, pilosa, crifpa, placeofa, reptans, parasitica, ciliata, eburnea, cornuta, boricata, anguina, coreoides, tulipifera, tabulum, ternata, cirrata, and opuntioides.

66. Pennatula, the Sea-pen.

Animal not fixed, of various shapes; supported by a bony part within; naked at the base; the upper part having generally lateral ramifications furnished with rows of tubular denticles, with radiate polypes from each tube.

There are 18 species, viz. coccinea, grifea, phlophorea, pilosa, rubra, mirabilis, fagitta, antennina, flellfera, phaloides, arundinacea, scipio, juncea, grandis, argentea, encrinus, cynomorium, and reniformis.

67. Hydra, the Polype.

Animal fixing itself by the base; linear, gelatinous, naked, contractile, and furnished with fæceous tentacles; inhabiting fresh waters, and producing its deciduous offspring from its sides. (Vid. fig. 15.)

These animals are among the most curious productions of nature, chiefly as exhibiting the most surprising example of diffused vitality. Though not so formidable as the hydra destroyed by Hercules, they are rendered equally prolific by being cut in pieces.

There are about five species, viz. viridis, fusca, grifea, gelatinosa, and pallens.

The three first species are those on which the greatest number of experiments have been made; and their shapes are so various, that it is by no means easy to describe them. They are generally found in ditches. Whoever has carefully examined these when the sun is very powerful, will find many little transparent lumps of the appearance of jelly, and size of a pea, and flatted upon one side. The same kind of substances are likewise to be met with on the under side of the leaves of plants that grow in such places. These are the polypes in a quiescent state, and apparently inanimate. They are generally fixed by one end to some solid substance, with a large opening, which is the mouth, at the other, having several arms fixed round it, projecting as rays from the centre. They are slender, pellucid, and capable of contracting themselves into very small compass, or of extending to a considerable length. The arms are capable of the same contraction and expansion as the body, and with these they lay hold of minute worms and insects, bringing them to the mouth, and swallowing them. The indigestible parts are again thrown out by the mouth.

The green polype was that first discovered by M. Trem-viridis, bley; and the first appearances of spontaneous motion were perceived in its arms, which it can contract, expand, and twist about in various directions. On the first appearance of danger they contract to such a degree, that they appear little longer than a grain of land, of a fine green colour, the arms disappearing entirely. Soon afterwards, he found the grifea, and afterwards the fusca. The bodies of the viridis and grifea diminish almost insensibly from the anterior to the posterior extremity; but the fusca is for the most part of an equal size for two thirds of its length from the anterior to the posterior extremities, from which it becomes abruptly smaller, and then continues of a regular size to the end. These three kinds have at least six, and at most twelve or thirteen arms. They can contract themselves till their bodies do not exceed one fourth of an inch in length, and they can stop at any intermediate degree of expansion or contraction. They are of various sizes, from an inch to an inch and a half long. Their arms are seldom longer than their bodies, though some have them an inch, and some even eight inches long. The thickness of their bodies decreases as they extend themselves, and vice versa; and they may be made to contract themselves either by agitating the water in which they are contained, or by touching the animals themselves. When taken out of the water they all contract too much, that they appear only like a little lump of jelly. They can contract or expand one arm, or any number of arms, independent of the rest; and they can likewise bend their bodies or arms in all possible directions. They can also dilate or contract their bodies in various places, and sometimes appear thick set with folds, which, when carelessly viewed, appear like rings. Their progressive motion is performed by that power, which they have of contracting and dilating their bodies. When about to move, they bend down their heads and arms, lay hold by means of them on some other substance to which they design to fasten themselves; then they loosen their tail, and draw it towards the head; then either fix it in that place, or stretching forward their head as before, repeat the same operation. They ascend or descend at pleasure in this manner upon aquatic plants, or upon the sides of the vessel in which they are kept; they sometimes hang by the tail from the surface of the water, or sometimes by one of the arms; and they can walk with ease upon the surface of the water. On examining the tail with a microscope, a small part of it will be found to be dry above the surface of the water; and, as it were in a little concave space, of which the tail forms the bottom; so that it seems to be suspended on the surface of the water on the same principle that a small pin or needle is made to swim. When a polype, therefore, means to pass from the sides of the glass to the surface of the water, it has only to put that part out of the water by which it is to be supported, and to give it time to dry, which it always does upon these occasions; and they attach themselves so firmly by the tail to aquatic plants, stones, &c. that they cannot be easily disengaged: they often further strengthen these attachments. The stomach of the polype is a kind of bag or gut into which the mouth opens, and goes from the head to the tail. This, in a strong light, is visible to the naked eye, especially if the animal be placed between the eye and a candle; for these animals are quite transparent whatever their colour may be: the stomach, however, appears to more advantage through a powerful magnifier. M. Trembley, by cutting one of these animals transversely into three parts, satisfied himself that they were perforated throughout. Each piece immediately contracted itself, and the perforation was very visible through a microscope. The skin which encloses the stomach is that of the polype itself; so that the whole animal, properly speaking, consists only of one skin, in the form of a tube, and open at both ends. No vessels of any kind are to be distinguished.

The mouth is situated at the anterior end in the middle between the shooting forth of the arms, and assumes different appearances according to circumstances; being sometimes lengthened out in the form of a nipple, at others appearing truncated; sometimes the aperture is quite closed, at others there is a hollow; though at all times a small aperture may be discovered by a powerful magnifier.

The skin of a polype, when examined with a microscope, appears like flagegreen, or as if covered with little grains, more or less separated from each other, according to the degree of contraction of the body. If the lips of a polype be cut transversely, and placed so that the cut part of the skin may be directly before the microscope, the skin throughout its whole thickness will be found to consist of an infinite number of grains, and the interior part is found to be more flaggreened than the exterior one; but they are not strongly united to each other, and may be separated without much trouble. They even separate of themselves, though in no great numbers, in the most healthy animals of this kind; for where they are observed to separate in large quantities, it is a symptom of a very dangerous disorder. In the progress of this disorder, the surface of the polype becomes gradually more and more rough and unequal, and no longer well defined or terminated as before. The grains fall off on all sides, the body and arms contract and dilate, and assume a white shining colour; and at last the whole dissolves into a heap of grains, which is more particularly observed in the green polype. By a careful examination we find, that the skin of the polype is entirely composed of grains, cemented by means of a kind of gummy substance; but it is to the grains entirely that the polype owes its colour. The structure of the arms is analogous to that of the body; and they appear flaggreened, when examined by the microscope, whether they be in a state of contraction or expansion; but, if very much contracted, they appear more flaggreened than the body, though almost quite smooth when in their utmost state of extension. In the green polype the appearance of the arms is continually varying; and these variations are more sensible towards the extremity of the arm than at its origin, but more scattered in the parts further on. The extremity is often terminated by a knob, the hairs of which cannot be observed without a powerful magnifier. They have a remarkable inclination for Zoophita, turning towards the light, so that if that part of the glass, on which they are, be turned from the light, they will quickly remove to the other.

That species named the fijca has the longest arms, fijca, and makes use of the most curious manoeuvres to seize its prey. They are best viewed in a glass seven or eight inches deep, when their arms commonly hang down to the bottom. When this or any other kind is hungry, it spreads its arms in a kind of circle to a considerable extent, including in this, as in a net, every insect which has the misfortune to come within the circumference. While the animal is contracted by seizing its prey, the arms are observed to swell like the muscles of the human body when in action. Though no appearance of eyes can be observed in the polype, they certainly have some knowledge of the approach of their prey, and shew the greatest attention to it as soon as it comes near them. It seizes a worm the moment it is touched by one of the arms; and in conveying it to the mouth, it frequently twists the arm into a spiral like a cork-crew, by which means the insect is brought to the mouth in a much shorter time than otherwise it would be; and so soon are the insects on which the polypes feed killed by them, that M. Fontana thinks they must contain the most powerful kind of poison; for the lips scarce touch the animal when it expires, though there cannot be any wound perceived on it when dead. The worm, when swallowed, appears sometimes fliggle, sometimes double, according to circumstances. When full, the polype contracts itself, hangs down as in a kind of stupor, but extends again in proportion as the food is digested, and the excrementitious part is discharged. The bodies of the insects, when swallowed, are first macerated in the stomach, then reduced into fragments, and driven backwards and forwards from one end of the stomach to the other, and even into the arms, which, as well as the other parts of this remarkable creature, are a kind of hollow guts or stomachs. In order to observe this motion, it is best to feed the polypes with such food as will give a lively colour; such, for instance, as those worms which are furnished with a red juice. Some bits of a small black snail being given to a polype, the substance of the skin was soon dissolved into a pulp consisting of small black fragments; and on examining the polype with a microscope, it was found that the particles were driven about in the stomach, and that they passed into the arms, from thence back into the stomach; then to the tail, from whence they passed again into the arms, and so on. The grains of which the body of the polype consists, take their colour from the food with which it is nourished, and become red or black as the food happens to afford the one or the other. They are likewise more or less tinged with these colours in proportion to the strength of the nutritive juices; and it is observable that they lose their colour if fed with aliment of a colour different from themselves. They feed on most insects, and fish or flesh, if cut into small bits. Sometimes two polypes lay hold of the same worm, and each begins to swallow its own end till their mouths meet and the worm breaks. But should this happen not to be the case, the one polype will sometimes devour the other along with its portion. It appears, however, that the stomach of one polype is not fitted for diluting the substance of another; for the one which is swallowed always gets clear again after being imprisoned an hour or two.

The manner in which the polypes generate is most perceptible in the grifia and fusca, as being considerably larger than the viridis. If we examine one of them in summer, when the animals are most active, and prepared for propagation, some small tubercles will be found proceeding from its sides, which constantly increase in bulk, until at last in two or three days they assume the figure of small polypes. When they first begin to shoot, the excrescence becomes pointed, assuming a conical figure, and deeper colour than the rest of the body. In a short time it becomes truncated, and then cylindrical, after which the arms begin to shoot from the anterior end. The tail adheres to the body of the parent animal, but gradually grows smaller, until at last it adheres only by a point, and is then ready to be separated. When this is the case, both the mother and young ones fix themselves to the sides of the glass, and are separated from each other by a sudden jerk. The time requisite for the formation of the young ones is very different, according to the warmth of the weather and the nature of the food eaten by the mother. Sometimes they are fully formed, and ready to drop off in 24 hours; in other cases, when the weather is cold, 15 days have been requisite for bringing them to perfection.

It is remarkable, that there is a reciprocal communication of food between the young and old, before they be separated. The young ones, as soon as they are furnished with arms, catch prey for themselves, and communicate the digested food to the old ones, who on the other hand do the same to the young ones. This was fully verified by the following experiment. One of the large polypes of the fusca kind being placed on a slip of paper in a little water, the middle of the body of a young one growing out from it was cut open; when the superior part of that end which remained fixed to the parent was found to be open also. But cutting over the parent polype on each side of the throat, a short cylinder was obtained, open at both ends; which being viewed through a microscope, the light was observed to come through the young one into the stomach of the old one. On cutting open the portion of the cylindrical portion lengthwise, not only the hole of communication was observed, but one might see through the end of the young one also. On changing the situation of the two pieces, the light was seen through the hole of communication. This may be seen between the parent polype and its young ones after feeding them; for after the parents have eaten, the bodies of the young ones swell as if they themselves had been eating.

The polypes produce young ones indiscriminately from all parts of their bodies, and five or six young ones have frequently been produced at once; nay, M. Trembley has observed nine or ten produced at the same time.

Nothing like copulation among these creatures was ever observed by M. Trembley, though for two years he had thousands of them under his inspection. To be more certain on this subject, he took two young ones the moment they came from their parent, and placed them in separate glasses. Both of them multiplied, not only themselves, but also their offspring, which were separated and watched in the same manner to the seventh generation. They have even the same power of generation while adhering to their parent. In this state the parent, with its children and grandchildren, exhibits a singular appearance, looking like a thrub thick let with branches. Thus several generations sometimes are attached to one another, and all of them to one parent. Mr Adams gives a figure of one polype with 19 young ones hanging at it; the whole group being about one inch broad, and one inch and a half in length; the old polype ate about 12 monoculars per day, and the young ones about 20 among them.

When a polype is cut transversely or longitudinally into two or three parts, each part in a short time becomes a perfect animal; and so great is this prolific power, that a new animal will be produced even from a small portion of the skin of the old one. If the young ones be mutilated while they grow upon the parent, the parts so cut off will be reproduced; and the same property belongs to the parent. A truncated portion will send forth young ones before it has acquired a new head and tail of its own, and sometimes the head of the young one supplies the place of that which should have grown out of the old one. If we slit a polype longitudinally through the head to the middle of the body, we shall have one formed with two heads; and by again slitting these in the same manner, we may form one with as many heads as we please.

A still more surprising property of these animals is, that they may be grafted together. If the truncated portions of a polype be placed end to end, and gently pulled together, they will unite into a single one. The two portions are first joined together by a slender neck, which gradually fills up and disappears; the food passing from one part into the other; and thus we may form polypes, not only from different portions of the same animal, but from those of different animals. We may fix the head of one to the body of another, and the compound animal will grow, eat and multiply, as if it had never been divided. By pushing the body of one into the mouth of another, so far that their heads may be brought into contact, and kept in that situation for some time, they will at last unite into one animal, only having double the usual number of arms. The hydra fusca may be turned inside out like a glove, at the same time that it continues to eat and live as before. The lining of the stomach now forms the outer skin, and the former epidermis constitutes the lining of the stomach. If previous to this operation the polype have young ones attached to it, such as are newly beginning to vegetate turn themselves inside out, while the larger ones continue to increase in size till they reach beyond the mouth of the parent, and are then separated in the usual manner from the body. When thus turned, the polype combines itself in many different ways. The fore part frequently closes and becomes a supernumerary tail. The animal, which was at first straight, now bends itself, so that the two tails resemble the legs of a pair of compasses, which it can open and shut. The old mouth is placed as it were at the joint of the compasses, but loses its power of action; to supply which, Species. Infusoria.

A new one is formed in its neighbourhood, and in a little time there is a new species of hydra found with several mouths.

The sides of a polype which has been cut through in a longitudinal direction, begin to roll themselves up, usually from one of the extremities, with the outside of the skin inwards; but in a little time they unroll themselves, and the two cut edges join together, sometimes beginning at one extremity, and sometimes approaching throughout their whole length. As soon as the edges join, they unite so closely that no fear can be perceived. If a polype be partly turned back, the open part closes, and new mouths are formed in different places. Every portion of a polype is capable of devouring insects, almost as soon as it is cut off, and the voracity of the whole tribe is astonishing; for Mr Adams observes, that most of the insects on which they feed bear the same proportion to the mouth of a polype, that an apple the size of a man's head bears to the mouth of a man.

The hydra pallens is very rarely met with, and is described by Mr Roffelle. It is of a pale yellow colour, growing gradually smaller from the bottom; the tail is round or knobbed; the arms are about the length of the body, of a white colour, generally seven in number, and are apparently composed of a chain of globules. The young are brought forth from all parts of its body.

The order Zoophyta contains 15 genera and 489 species.

Order V. Infusoria.

We have already, under the article Animalcule, treated of the general character and habits of the animals composing this order, and we can add little here to what has been said in that article. We shall therefore merely give the classification of the genera and species, and briefly notice a few of the more remarkable individuals.

Few writers have written expressly on this order; but the principal are Muller, Brugiere, in the Encyclopedie Methodique, and Baker and Adams on the Microscope.

68. Brachionus.

Body contractile, covered with a shell, and furnished with rotatory cilia.

There are about 12 species, viz. urceolaris, patella, cirratus, tripus, uncinatus, mucronatus, cerminus, calyciflorus, tubifex, quadridentatus, patina, and striatus.

The patina is extremely bright and splendid, has a large body, a crystalline and nearly circular shell, without either incision or teeth, only towards the apex it falls in so as to form a smooth notch. A double glittering organ, with ciliated edges, projects from the apex; both of them of a conical figure, and standing as it were upon a pellucid substance, which is divided into two lobes, between which and the rotatory organ there is a silver-coloured crenulated membrane. Two small claws may likewise be discovered near the mouth.

The striatus has an oblong, pellucid shell, capable of altering its figure. The apex is truncated, with five small teeth on the edge of it, 12 longitudinal streaks down the back, the base obtuse and smooth. The teeth are occasionally protruded or retracted; and there are two small spines or horns on the other side of the shell. The animal itself is of a yellow colour, crystalline, and muscular; now and then putting out from the apex two or three little bundles of playing hairs, the two lateral ones shorter than that in the middle; on the outer side we may observe a forked deglutatory muscle, and two rigid points when the apex is drawn in. It is found in sea water.

69. Vorticella.

Body contractile, naked, and furnished with ciliate, rotatory organs.

There are about 57 species, which are arranged under three sections.

A. Seated on a pedicle or stem.

29 species, viz. * racemosa, * polyypina, * anastatica, conglomerata, * pyraria, * opercularia, * tuberosa, bianca, bellis, * umbellaria, * berberina, digitalis, fasciculata, annularis, nutans, gemella, * nebulosa, * convallaria, * lunaris, * globularia, inclinata, ringens, * pyriformis, fellata, vaginata, * citrina, cyathina, putrida, and patellina.

B. Furnished with a tail.

14 species, viz. * flocculosa, * socialis, * stentorea, * hyacinthina, auriculata, * furcata, fenta, * catulus, felis, vermicularis, * macroura, * rotatoria, * lacinalata, and fasciculata.

C. Without tail or stem.

14 species, viz. * ampulla, * crateraria, caniculata, * nafuta, * crateriformis, * truncatella, * limacina, * difficilis, cornuta, * cincta, * polymorpha, * viridis, * bursata, and * nigra.

The polyypina, when viewed through a small magnifier, appear like so many little trees; the upper part, or heads, are egg-shaped, the top truncated, the lower part filled with intestines; the branches thick set with little knobs. Vide fig. 16.

The fasciculata has a rotatory organ, which may sometimes be seen projecting beyond the aperture; there ia a little head at the apex, and the pedicle is twisted and very slender. A congealed green mass which is often found swimming about in ditches is composed of myriads of these animals, which are not visible to the naked eye, and when magnified appear like a bundle of green flowers.

The socialis, when considerably magnified, appears like a circle surrounded with crowns or ciliated heads, tied by small thin tails to a common centre, from whence they advance towards the circumference, where they turn very briskly, occasioning a kind of whirlpool, which brings its food. When one of them has been in motion for some time, it stops, and another begins; sometimes two or three may be perceived in motion at once; they are frequently to be met with separate, with the tail sticking in the mud. The body contracts and dilates very much, so as sometimes to have the appearance of a cudgel, at others to assume almost a globular form. The floculosa appears to the naked eye like a yellow globule adhering to the ceratophyllon like a little flower or a heap of yellow eggs. When magnified, they are seen to consist of a congeries of animalcula constituting a sphere from a mouldy centre. They contract and extend their bodies either alone or in society, and excite a vortex in the water by means of a disk. When they quit the society and act singly, they may be observed to consist of a head, abdomen and tail; the head being frequently drawn back into the abdomen so far that it cannot be seen, only exhibiting a broad kidney-shaped disk standing out. The abdomen is oblong, oval, and transparent; the tail sharp, twice as long as the abdomen, sometimes rough and annulated, or altogether smooth.

70. Trichoda. Animal invisible to the naked eye, pellucid, hairy, or horned.

There are about 60 species, which are divided into three sections.

A. Hairy.

47 species, viz. grandinella, *cometa, *granata, *fol, *bamba, orbis, urnula, urinarium, *trigona, tinea, *pubes, *proteus, *gibba, *patens, *uvula, fulcata, *anas, *farcimen, *linter, *vermicularis, *melita, *fimbriata, camelus, *ratus, inquinilus, *innata, transfuga, ciliata, *cyclidium, *pulex, *lynceus, *charon, *cimex, pellionella, angulus, urufa, femulina, pupa, *pocillum, clavus, *muculus, *delphinus, clava, cuniculus, *pilcis, larus, and *longicauda.

B. Furnished with cirri.

Four species, viz. *aeacus, *ludis, fanaio, and volutator.

C. Horned.

Nine species, viz. lyncaster, *histro, *cypris, *patalia, *pullaster, *mytilus, lepus, filurus, and calvium.

The grandinella is a very small pellucid globule, with the interstices scarcely visible; the top of the surface furnished with several small brittle not easily discoverable, as the creature has a power of extending or drawing them back in an instant. It is found in pure water as well as in infusions of vegetables.

The fol is small, globular, and crystalline; beset everywhere with diverging rays longer than the diameter of the body; the inside full of molecules. The body contracts and dilates, but the creature remains confined to the same spot. It was found with other animalcules in water which had been kept three weeks.

The proteus is that which Mr Baker distinguishes by the same name, and of which an account is given under the article Animalcule. It is found in the filmy matter adhering to the sides of the vessel in which vegetables have been infused, or animal substances preserved. That described by Mr Adams was discovered in the lime produced from the water where small fishes, water snails, &c. had been kept. The body resembled that of a snail, the shape being somewhat elliptical, but pointed at one end, while from the other proceeded a long, slender, and finely proportioned neck, of a size suitable to the rest of the animal.

71. Cercaria. Animal invisible to the naked eye, pellucid, and furnished with a tail.

There are 13 species; viz. *cyrinus, *inquieta, *lemna, *turbo, *podura, *mutabilis, catellus, *lupus, *vermicularis, pleuronectis, *tripus, cyclidium, and tenax.

The lemna varies its form so much, that it might be mistaken for the proteus of Baker, described under the article Animalcule; though in fact it is totally different. The body sometimes appears of an oblong, sometimes of a triangular, and sometimes of a kidney-shape. The tail is generally short, thick, and annulated; but sometimes long, flexible, cylindric, and without rings; vibrating, when stretched out, with so much velocity, that it appears double. A small pellucid globule, which Muller supposes to be its mouth, is observable at the apex; and two black points not easily discovered, he thinks, are its eyes. It walks slowly after taking three or four steps, and extends the tail, erecting it perpendicularly, shaking and bending it, in which state it very much resembles a leaf of the lemna.

72. Leucophra. Animal invisible to the naked eye, and everywhere ciliate.

There are eight species; viz. *conflictor, *vesiculifera, acuta, fluxa, armilla, *cornuta, *heteroclitia, and nodulata.

73. Gonium. Animal very simple, flat, angular, but invisible to the naked eye.

There are five species; viz. *pectorale, pulvinatum, polysphericum, truncatum, and rectangulum.

The pectorale is found in pure water, and moves alternately towards the right and left. It is quadrangular and pellucid, with 16 spherical molecules, of a greenish colour, set in a quadrangular membrane, like the jewels in the breast-plate of the high priest, reflecting light on both sides.

74. Colpoda. Animal invisible to the naked eye, very simple, pellucid, finuate.

There are seven species; viz. lamella, rostrum, cucullus, *meleagris, *cucullus, ren, *pyrum, and hypocrepis.

The cucullus is found in vegetable infusions, and in fecal hay, moving in all directions, and commonly with great velocity. It is very pellucid, and has a well-defined margin, filled with little bright vehicles differing in size, and of no certain number. Its figure is commonly oval, with the top bent into a kind of beak, sometimes oblong, but most commonly obtuse. It has in the inside from 8 to 24 bright little vehicles not discernible in such as are young. Some have supposed posed these to be animalcules which this creature has swallowed; but Mr Muller is of opinion that they are its offspring. When this creature is near death by reason of the evaporation of the water, it protrudes its offspring with violence. From some circumstances it would seem probable that this animalcule calls its skin, as is the case with some insects.

75. Paramesium.

Worm invisible to the naked eye, simple, pellucid, flattened, oblong.

There are seven species; viz. * aurelia, * chrysalis, * oviferum, * marginatum, caudatum, anceps, and acutum.

The aurelia is membranaceous, pellucid, and four times longer than it is broad; the fore part obtuse and transparent; the hind part filled with molecules. It has somewhat the appearance of a gnatlet, by reason of a fold which goes from the middle to the apex, and is of a triangular figure. It moves in a rectilinear and vacillatory manner. It is found in ditches where there is plenty of duckweed; and will live many months in the same water without any renewal of it.

76. Cyclidium.

Worm invisible to the naked eye, very simple, pellucid, flat, orbicular or oval.

There are seven species; viz. * bulla, milium, glaucoma, * radians, rostratum, * nucleus, and pediculus.

77. Bursaria.

Worm very simple, membranaceous, hollow.

There are three species; viz. truncatella, * hirundinella, and * duplella.

78. Vibrio.

Worm invisible to the naked eye; very simple, round, elongated.

There are 20 species; viz. lineola, bacillus, undula, vermiculus, intertinum, * lunula, malleus, * serpentinus, * aceti, * glutinis, * anguillula, utriculus, falcio, colymbus, cygnus, * anler, * odor, falx, diffusus, and * proteus.

The anler is found in water where duckweed grows. The trunk is elliptic, round, and without any inequality on the sides. It is full of molecules; the hind part sharp and bright; the fore part produced into a bending neck, longer than the body; the apex whole and even, with blue canals passing between the marginal edge, occupying the whole length of the neck; and in one of them a violent deflection of water to the beginning of the trunk is observable. It moves the body slow, but the neck more briskly.

79. Enchelis.

Worm invisible to the naked eye; very simple, cylindrical.

There are 15 species; viz. viridis, * punctifera, nodulosa, sarcimen, femulum, ovulum, pyrum, fulus, frutillis, * caudata, epitomium, * retrograda, * truncus, spatula, and papula.

80. Bacillaria.

Body consisting of cylindrical straw-like filaments, placed parallel to each other, and frequently changing their position.

There is only one species; viz. paradoxa.

81. Volvox.

Worm invisible to the naked eye; simple, pellucid, spherical.

There are nine species; viz. globulus, pilula, * spharula, uva, * lunula, dimidiatus, * globator, pileus, and bulla.

The globator, or spherical membranaceous volvox, is globator, found in great numbers in the infusions of hemp and tremella, and in flagrant waters in spring and summer. It was first observed and described by Leeuwenhoek; but the descriptions of it given by authors differ considerably from each other. The following is that of Mr Baker. "There is no appearance of either head, tail, or fins. It moves in every direction, backwards, forwards, up or down, rolling over and over like a bowl, spinning horizontally like a top, or gliding along smoothly without turning itself at all: sometimes its motions are very slow, at other times very swift; and when it pleases it can turn round as upon an axis very nimbly, without moving out of its place. The body is transparent, except where the circular spots are placed, which are probably its young. The surface of the body in some is as if all dotted over with little points, and in others as if granulated like shagreen. In general it appears as if let round with short moveable hairs." Another author informs us, that "they are first very small, but grow so large that they can be discerned with the naked eye; they are of a yellowish green colour, globular figure, and in substance membranaceous and transparent; and in the midst of this substance several small globes may be perceived. Each of these are smaller animalcules, which have also the diaphanous membrane, and contain within themselves still smaller generations, which may be distinguished by means of very powerful glasses. The larger globules may be seen to escape from the parent, and then increase in size."

This little animal appears like a transparent globule of a greenish colour, the fetus being composed of smaller greenish globules. In proportion to its age it becomes whiter and brighter, and moves slowly round its axis; but to the microscope its surface appears as if granulated; the roundest molecules fixed in the centre being largest in those that are young. The exterior molecules may be wiped off, leaving the membrane naked. When the young ones are of a proper size, the membrane opens, and they pass through the fissure, after which the mother melts away. Sometimes they change their spherical figure, and become flat in several places. They They contain from 8 to 30 and 40 globules within the membrane.

82. Monas.

Worm invisible to the naked eye; most simple, pellucid, resembling a point.

There are five species; viz., *atomus, punctum, *micro, *lens, and ternio.

This order contains 15 genus and 229 species.

How many kinds of these invisibles there may be (says Mr Adams), is yet unknown; as they are distinguished from those which are barely invisible to the naked eye, to such as resist the force of the microscope as the fixed stars do that of the telescope, and with the greatest powers hitherto invented, appear only as so many moving points. The smallest living creatures our instruments can show, are those which inhabit the waters; and though animalcula equally minute may fly in the air, or creep upon the earth, it is scarce possible to get a view of them; but as water is transparent, by confining the creatures within it we can more easily observe them by applying a drop of it to the glases.

Animalculae in general are observed to move in all directions with equal ease and rapidity; sometimes obliquely, sometimes straight forward; sometimes moving in a circular direction, or rolling upon one another, removing backwards and forwards through the whole extent of the drop, as if diverting themselves; at other times greedily attacking the little parcels of matter they meet with. Notwithstanding their extreme minuteness, they know how to avoid obstacles, or to prevent any interference with one another in their motions: sometimes they will suddenly change the direction in which they move, and take an opposite one; and by inclining the glass on which the drop of water is, as it can be made to move in any direction, so the animalculae appear to move as easily against the stream as with it. When the water begins to evaporate, they flock towards the place where the fluid is, and show a great anxiety and uncommon agitation of the organs with which they draw in the water. These motions grow languid as the water fails, and at last cease altogether, without a possibility of renewal if they be left dry for a short time. They sustain a great degree of cold as well as insects, and will perish in much the same degree of heat that destroys insects. Some animalculae are produced in water at the freezing point, and some insects live in snow. By mixing the least drop of urine with the water in which they swim, they instantly fall into convulsions and die.

The same rule seems to hold good in these minute creatures, which is observable in the larger animals, viz. that the larger kinds are less numerous than such as are smaller; while the smallest of all are found in such multitudes, that there seem to be myriads for one of the others. They increase in size, like other animals, from their birth until they have attained their full growth; and when deprived of proper nourishment, they in like manner grow thin and perish."

EXPLANATION OF FIGURES.

Fig. 1. *Acaris Lumbricoides*, entire, and nearly of its natural size; *a*, the head; *b*, the tail; *c*, the depressed band; *d*, the punctiform aperture; *e*, the line extending from the head to the tail; *f*, the gyrated apparatus as it appears through the skin of the worm.

Fig. 2. Represents the *vulva* of the worm in their natural situation; *a*, the head; *b*, the gullet; *c*, the intestinal canal; *d*, the lines of the body of the worm; *e*, the uterus, and its convoluted apparatus.

Fig. 3. *Acaris Vermicularis* of its natural size.

Fig. 4. The same viewed by the microscope; *a*, the head; *b*, the tail; *c*, the proboscis; *d*, the intestinal canal; *e*, hollow tube; *f*, the ovaria.

Fig. 7. A portion of the *Tenia Solium*, of its natural size, and usual appearance; *a*, the marginal ocella.

Fig. 8. *a*, the head enlarged by the microscope; *b*, a full view of the head when very much magnified; *a*, the ocella at the base; *c*, the mouth.

Fig. 9. *Siponulus Sacculus*, of its natural appearance.

Fig. 10. *Lophius Depilans*, or Sea-hare.

Fig. 11. *Holothuria Tremula*.

Fig. 12. *Alterias Caput Medusa*, or Arborecent Sea-flar.

Fig. 13. *Echinus Felulentus*, or common Sea-urchin.

Fig. 14. *Tubularia Magnifica*, as it proceeds from its native rocks; *a*, the animal with its tentacula fully expanded from the tube; *b*, another with the tentacula collapsed; *c*, one with the tentacula nearly withdrawn into the tube; *d*, the animal with the tentacula entirely withdrawn; *e*, *e*, *e*, probably actinia.

Fig. 15. *Hydra Grifea*, or Fresh-water Polype, magnified; *a*, the mouth; *b*, the attached part; *c*, *c*, *c*, &c., the arms; *e*, the transparent body.

Fig. 16. *Vorticella Polypina*, magnified.

ERRATUM.

The Genus Scyllae is inadvertently omitted in the arrangement of the species. It should have been placed next Lernaea, with the following character.

*Scyllae*. Body compressed and grooved on the back; mouth consisting of a terminal toothless aperture; tentacula 3 on each side, placed beneath.

There are two species, viz., pelagica and goniphodensis.

INDEX. ### Index

#### A

**ACTINIA**, p. 335 No. 39 **Alcyonium**, 336 77 **Amphitrite**, ib. 61 **Anisogaster**, ib. 75 **Aphrodita**, ib. 60 **Aculeata**, 353 **Argus**, fea, 351 **Ascarides**, 337 **Ascaris**, 334 15 **Lumbricoides**, 338 **Vermicularis**, 339 **Mammalium**, ib. **Avium**, ib. **Reptilium**, ib. **Piscium**, ib. **Lumbrici**, 340 **Ascidia**, 335 43 **Papillofa**, 348 **Intestinalis**, ib. **Asterias**, 336 68 **Caput medusae**, 355

#### B

**Bacillaria**, 337 **Brachionus**, 337 85 **Striatus**, 362 **Patina**, ib. **Burseria**, 337 94

#### C

**Caryophyllaceus**, 334 27 **Cellpora**, ib. 73 **Cercaria**, 337 88 **Lemma**, 363 **Clava**, 335 40 **Clio**, 336 56 **Colpoda**, 337 91 **Cucullus**, 363 **Corallina**, 336 81 **Cucullanus**, 334 26 **Mammalium**, 342 **Butonis**, ib. **Avium**, ib. **Piscium**, ib. **Cuttle-fish**, 352 **Cuvier's classification of worms**, 11 **Cyelidium**, 337 93 **Glaucoma**, 364

#### D

**Dagysia**, 335 45 **Deris**, ib. 47 **Deu-worm**, 346 **Doris**, 335 50 **Argo**, 351 **Dracunculus**, 340

#### E

**Earthworm**, p. 346 **How different from alcaris lumbricoides**, No. 36 **Echinorhynchus**, 334 24 **Mammalium**, 341 **Avium**, ib. **Reptilium**, ib. **Piscium**, ib. **Echinus**, 336 69 **Eculeatus**, 356 **Eggs**, fea, ib. **Enchelis**, 337 96

#### F

**Fasciola**, 334 28 **Hominis**, 342 **Mammalium**, ib. **Heptica**, ib. **Avium**, ib. **Reptilium**, ib. **Piscium**, ib. **Loliginis**, 334 18 **Filaria**, 349 **Medinenis**, 342 **Fluke**, 342 **Flufira**, 336 79 **Furia**, 333 31 **Infernalis**, 345

#### G

**Generic characters**, 12 **Of the intestinalis**, 13 **Molluscis**, 14 **Zoophyta**, 15 **Infusoria**, 16 **Gonium**, 337 90 **Pectorale**, 303 **Gordius**, 335 32 **Aquaticus**, 345 **Gorgonia**, 336 76 **Gourd worm**, 342 **Guinea worm**, 340

#### H

**Herua**, 334 25 **Hair-worm**, 345 **Hare**, fea, 350 **Hedgehogs**, fea, 356 **Helminthology**, definition of, 1 **Division of**, 2 **Intestina**, 3 **Mollusca**, 4 **Tetrae**, 5 **Zoophyta**, 6 **Infusoria**, 7

#### I

**Hydatids**, P. 342, 343 **Hydra**, P. 336 84 **Viridis**, 359 **Fulca**, 360

#### L

**Lapula**, 335 49 **Leech**, medicinal, 345 **Mode of applying**, 34 **Horfe**, 316 **Lernae**, 336 59 **Leucophrus**, 337 89 **Ligula**, 334 21 **Limax**, 335 48 **Agrestis**, 349 **Linguatula**, 334 44 **Lobaria**, 336 58 **Lucernaria**, ib. 67 **Lumbricus**, 335 45 **Terrestris**, 346

#### M

**Madrepora**, 336 71 **Mammaria**, 335 42 **Mat-weed**, fea, 318 **Medusa**, 336 66 **Millipora**, ib. 72 **Mollusca**, P. 335, 348 **Monas**, 337 99

#### N

**Nair**, 336 64 **Nereis**, ib. 63 **Noctiluca**, 354 **Nettles**, fea, ib. **Onchidium**, 335 57 **P.**, P.