a piece of defensive armour worn by horsemen both in war and in tournaments. It anciently covered both the head and face, only leaving an aperture in the front secured by bars, which was called the visor. The title of this article was formerly bestowed on a much larger group of animated beings than that to which we here restrict it. The Linnaean group of *Vermes* contained, in fact, the whole of the intestinal and other worms, the molluscan and testaceous tribes, the Zoophytes and Infusoria,—which now form the natural materials of many classes. We here apply it exclusively to the *Annelides*, or red-blooded vermes, of which the medicinal leech and earth-worm afford familiar examples. Bruguières and others have no doubt conjoined them, in comparatively recent times, with the intestinal tribes; and it was at one time our intention (see *Animal Kingdom*, vol. iii. p. 180 of this work) to have adopted that arrangement. But we now conceive it to be more advisable to follow the example of Cuvier, and, referring the latter to the radiated or zoophysical division, to include in the article *Helminthology* the Annelides alone. In truth, the intestinal tribes exhibit no organs of respiration, either tracheal or branchial,—no traces of a true circulation,—and their nervous system is extremely obscure. It will therefore become apparent, from the following definition, how greatly the Annelides differ from the creatures just named.
The Annelides or red-blooded worms form the first class of the articulated division of the animal kingdom. Their blood, of a red colour, resembling that of the vertebrated animals, circulates in a double system of closed vessels, that is, in arteries and veins. This system, though destitute of a heart properly so called, is sometimes provided with one or more distinct fleshy ventricles. Respiration is carried on through the medium of organs, which are sometimes external, occasionally developed beneath the surface of the skin, or sunk more deeply into the interior. They may all be presumed to breathe by means of branchiae; although the respiratory system, of the so-called Abranchial Order, is still unknown. The branchiae or respiratory organs of the greater number are external, and vary considerably in their size, form, number, and position. Their body, of a softish texture, is more or less elongated, and always divided into numerous rings or segments, of which the anterior, known under the name of head, scarcely differs from the others, except by the possession of a mouth, and of the principal organs of the senses. None of the Annelides possess articulated members properly so called, but in room of these many are furnished with setiferous mammillae, or fleshy projections, bearing bundles of hairs or bristles, and forming what may be called *pedes spurii*, of which the number is extremely various. These peculiar organs are sometimes composed of two parts, the one superior and dorsal, the other inferior and ventral. The muscular power resides in the interior, and is capable of producing only an undulatory or creeping movement,—the locomotive parts being incompetent to sustain the body. The organs of the mouth consist sometimes of parts resembling jaws, more or less developed,—sometimes of a simple tube. The organs of the external senses are composed of fleshy tentacula, sometimes articulated,—and of certain blackish points, not existing in all the species, regarded as eyes.
The nervous system consists of a double ganglionic cord, analogous to that of insects, as already described in our article *Entomology*. In regard to their natural habits, most of these creatures are aquatic (the Lumbrici or earthworms excepted). Some dwell in holes beneath the waters, other form tubes or tunnels of mud or other matters, or even transude from their own bodies a calcareous secretion, which forms around them a protecting covering. Considered sexually, they are for the most part hermaphrodite, and some require reciprocal communication.
It will be perceived, even from the preceding brief exposition, that the Annelides are animals of a very peculiar nature. Although their nervous system coincides with that of the other articulated classes, and although their bodies are likewise divided by transverse sections, yet their locomotive organs are entirely dissimilar to those of the Crustacea, Arachnides, and Insects. Their setiferous mammillae are merely retractile sheaths, and the hairs or bristles which they enclose are in no way comparable to the feet of the last-named classes, but are organs of a very different nature.
The Annelides are few in number compared with insects and other articulated classes, and the greater proportion are marine. Their possession of red blood is a singular character in animals so low in the scale, and one not possessed by the molluscous tribes, which are yet regarded as their superiors in other points of organisation. In regard to their external parts, we shall here indicate a few of the most important,—premising that the characters mentioned are not universal to the class, but rather
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1 From ἀγγειον, a worm, and λόγος, a discourse. 2 For a description of these primary divisions of the animal kingdom, see vol. iii. p. 179 of this work. 3 As to the external tube which the Chetopoda (by which term M. de Blainville designates the setiferous genera of the class Annelides) often inhabit, although it is frequently sufficiently regular and solid, it cannot however in any manner be compared to the shell of the Mollusca, not even where there is the greatest approximation, as in *Dentalium* and *Siligeria*. These tubes of the Chetopoda are always simple excretions from their body, which are by no means attached to it, and from which the animal may issue forth without dying immediately. We begin to observe something of this kind in the mucosity with which certain species line the hole hollowed in the mud or sand which they inhabit, as in the Arenicola, and some Lumbrici. This is analogous to the mucous pellicle of the tube of the Amphitrite and the Sabellae; but in the latter, surrounding this mucosity, is attached externally a stratum, more or less thick, consisting merely of mud or very fine grains of sand, or, in fine, of debris, more or less thick, of shells and larger grains of sand. These tubes are constantly open at both extremities; there are also some of them more regular, which are completely calcareous. The double opening is a character whereby they are distinguished from tubular shells, the summit of which, on the contrary, is constantly imbedded. These tribes, however, appear constantly to grow, after the manner of tubular shells, by laminae or strata extremely thin, placed inside of and out-edging one another. From this result strike marking the growth, more or less apparent outside; but we never remark longitudinal striæ on their surface, nor anything indicating the delicate working of the edges of a mouth, as in the Mollusca. This character alone might suffice to distinguish them from the true tubular shells; but to this we may add, that the constant perforation of the extremity of the tube of the Chetopoda never allows the animal, in growing and advancing in its tube, to form partitions there, whereas in the tubular shells the reverse is invariably the case. A final character which distinguishes the tubes of the Chetopoda is, that they are adherent, and fixed flatly, through a greater portion of their extent, on foreign bodies, which never takes place with the tubular shells." (Griffith's edition of Cuvier's *Animal Kingdom*, vol. xiii. p. 58.) We may add, that the young of the shell-bearing Mollusca are always born with shells, because that part forms, in fact, a portion of their skin; but there is no doubt that the young Annelides are produced in an exposed condition, and afterwards proceed, by a voluntary effort, to form their protecting habitations. confined to certain races. The head, in such as possess one, is a small anterior swelling, which bears the antennae commonly so called, and the eyes, and is distinct from the first segment of the body. The Nereids of Linnaeus are regarded by Latreille as the only Annelides of which the anterior segment merits the name of head, or possesses organs fit to be compared to eyes, more especially to those of the larvae of insects. These eyes are simple, extremely small, and appear like blackish points,—their number from two to four. Savigny indeed attributes eight to the leech tribe, but Latreille suspects that their structure is different from that of the Nereids. The organisation of the mouth varies greatly in the different orders. The parts called maxillae by Savigny are hard circumscribed parts, of a corneous or calcareous nature, to which Latreille does not accord the name of jaws. The latter author indeed seems to regard the Annelides as a suctorial rather than a masticating class. Most of them are of carnivorous habits, and live on the blood of other creatures. The trunk or sucker is a contractile fleshy portion, constituting the mouth, and containing the so-called jaws. The latter portions, however, being adherent to the inner coats of the sucker, and the latter being nothing more than a prolongation of the oesophagus, can scarcely be regarded as genuine jaws.
Several tribes have their branchiae uniformly spread over the extent of the body, or over its central portion, while others (and these usually dwell in tubes) bear those organs at their anterior extremity. In the erratic species, or such as are naked, and without fixed dwellings, they are usually disposed longitudinally along the sides of the body, there being one for each foot. Blood-vessels sometimes appear to spread into the setiform processes, and to convert them into respiratory organs.
We have already stated that Linnaeus placed the Annelides in his almost unlimited class of Vermes,—a vast and by no means well-combined group, which the later labours of Otho Frederick Muller, Pallas, and other naturalists, failed to cast into a more natural mould. The great Swedish naturalist separated the true Annelides from each other, placing one portion of the group in the order Intestina, and the other in that of Mollusca. In Cuvier's earliest work (Tableau Elementaire, &c. 1789), he restricted the class of worms to the Annelides and intestinal species, a mode of grouping previously practised by Bruguiere in the Encyclopedie Methodique. Subsequent investigations induced the French anatomist to raise the former to the rank of a separate class, which he named Vers a sans rouge, in a memoir read to the French Institute in 1802. On this same group Lamarck (Extrait du Cours, &c. 1812) bestowed the name of Annelides, which has since been very generally adopted. A slight disparity, however, still exists in the constitution of the Annelides, in the works of Cuvier and Lamarck, the former including in the class so named the genus Gordius, which the latter associates with the other Vermes.
But notwithstanding the valuable labours of these and other writers, the external structure of the Annelides cannot be said to have been at all rigorously determined, or viewed in relation to that of conterminous groups, till we received the fruits of Savigny's laborious and most delicate observations, originally presented to the Academy of Sciences. At that period Blainville was also occupied in the study of the same group, which, with the exception of the leeches, forms his class of Sétipodes. He published an extract from his labours in the course of the ensuing year. Oken, Leach, Latreille, Dugés, Audouin, Mlyne Edwards, and others, have likewise contributed to our knowledge of this curious and important class, in publications, to the majority of which we shall more particularly allude in the course of the present treatise.
In regard to the geographical distribution of the Annelides, our data are not yet sufficiently precise and numerous to admit of any satisfactory generalization. We have already said, that with the exception of the earthworms (and even these require a moist abode), all the known species are aquatic. We may add, that the great majority inhabit the saline waters of the ocean. Most of the Naidas, however, occur in fresh water, and some true Nereids are found in the lakes of North America. Annelides of some kind or other are met with in all quarters of the globe, and the species of many genera are very widely distributed; but others, such as the Amphionome, for example, are characteristic of, if not peculiar to, the warmer seas. Undoubtedly the most magnificent are native to the Indian shores. "It is in general on the coasts of the sea, in the midst of Thalassiphytes, in the infractuosities of Madrepores, in the sand, and particularly in mud, that the Chetopoda are to be found; and if some species are more commonly to be met with in the open sea, as, for instance, the Amphionome, named by M. Savigny Pleione vagans, it appears that they may have been drawn along with marine plants by the currents, as is the case with many other animals." Their natural movements are extremely slow, and may be compared to those of slugs, although their appendages for locomotion are much more numerous. The Nereids, however, not only creep in a kind of serpentine manner over the surface of solid bodies at the water's edge, but frequently swim very respectably, either by successive undulations of the body, after the manner of eels and serpents, or by agitating their appendages, and thus making these organs serve as ears.
The utility, in an economical point of view, of the Annelides in general to the human race, is by no means great. According to Pallas, the inhabitants of some parts of Belgium eat those portions of Aphrodita aculeata which compose the mouth; the Nereids and Arenicolae, as well as the earth-worms, are extensively employed as baits for fish, and the medicinal uses of the leech are notorious; but, with these, and, it may be, a few other exceptions, little can be said regarding the direct benefits derivable from this peculiar class. Its subjects, however, are by no means on that account the less important in the eyes of the philosophical naturalist.
Several of the Annelides possess a phosphoric property, from which Linnaeus named a certain species Nereis noctiluca. Others, characterized by the same attribute, have been more recently described by Sig. Viviani.
The presence or absence of the organs of motion, and the position of the branchiae, furnish natural characters of easy application, which modern zoologists have employed to signalize the primary groups. Lamarck divides the Annelides into three orders, les Apodes, les Antennes, and les Sédentaires,—and in the system of Cuvier they likewise form an equal number of orders, les Tubicoles, les Dorsobranches, and les Abranches. In both systems the Serpulae occupy the highest position in the scale. Savigny's arrangement of these animals consists of five orders, of which the author has as yet treated only of four, viz. les Néréidées, les Serpulées, les Lombricines, and les Hi-
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1 Système des Annelides, forming a portion of the great French work on Egypt. 2 Bulletin de la Soc. Phil. Mai et Juin 1818. 3 Phyllophanta maris quatuordecim lucoscentium animalculorum novis speciebus illustrata. Genève, 1805. He places the Aphrodites and Nereids at the head of the class. Latreille is also of opinion that these Annelides, especially the Nereids, so far as regards their external organisation, are entitled to precedence, and make the nearest approach to the articulated animals provided with feet, such as Insects and Crustacea.
We shall here, in as far as general arrangement is concerned, follow the system of Cuvier.
**Order I.—TUBICOLÆ**, Cuv.
Some form a calcareous homogeneous tube, supposed to result from transudation, like the covering of testaceous Mollusca, but which does not adhere by any muscular attachment; others construct a covering by agglutinating grains of sand, broken shells, and other debris, by means of a membrane, likewise the result of transudation; while a third group are surrounded by a tube of an entirely membranous or corneous nature.
**Genus Serpula**, Linn. The body is composed of numerous segments; its anterior portion is enlarged in the form of a disk, armed on either side by several bundles of stiff bristles; and on each side of the mouth is a fan-shaped plume of branchiae, usually adorned by lively colours. At the base of each plume is a fleshy filament, one or other of which is always prolonged and dilated at the extremity into a disk of various form, which serves as an operculum, and closes the overture of the tube whenever the contained creature chooses to retire. (Plate CCLXXV. fig. 3.) Of this genus the calcareous tubes cover, by their tortuous windings, the surface of stones, shells, and other submarine bodies. The species are widely distributed throughout the seas of Europe, India, and America. The largest are indigenous to the warmer climates of the globe. Little is known of their instinctive habits or natural economy. They are said to feed on aquatic animalcules, which they seize by means of their branchial tentacula.
Linnaeus, and most of the naturalists of his time, placed the Serpula among the testaceous Mollusca. They now constitute a numerous genus, of which several species occur in the European seas. They are very contractile, and are supposed to feed on animalcules. A well-known species, *S. contortuplicata* (Plate CCLXXV. fig. 1), has rounded tortuous tubes, of about three lines in diameter. Its operculum is tunnel-shaped, and its branchiae are often of a beautiful red, or varied with yellow and violet. Any object thrown into the sea is apt to be speedily covered by this species.
**Genus Spirobranchus**, Lam. Branchiae much less numerous than in the preceding genus (from three to four on each side), placed anteriorly in a somewhat radiated form. A pediculated operculum, with a flat summit placed between the branchiae. Tube testaceous, and rolled after the manner of a *Cornu ammonis*.
This genus is composed of very small species, which are found attached to fuci, shells, and other marine bodies. They frequently occur in great numbers, though always separate from each other. The animals are of a blood-red colour. We have figured the *Sp. nautiloides* of Lam. synonymous with the *Serpula spirorbis* of Linn. See Plate CCLXXV. figs. 2 and 4.
**Genus Sabella**, Cuv. *Amphitrite*, Lamarck. Body and fan-shaped branchiae resembling those of the preceding genus, but both the fleshy filaments adhering to the branchiae terminate in a point, and do not form an operculum; they are sometimes even wanting. Their tube is rarely calcareous, and seems often formed of grains of very fine clay or mud. Most of the ascertained species are of considerable size, and are remarkable for the extreme delicacy and lustre of their plumpy branchiae.
One of the most splendid of the genus is figured by Dr. Shaw under the title of *Tubularia magnifica*. It is found on various parts of the coast of Jamaica, adhering to the rocks. It is extremely wary, and when approached instantly recedes within its tube, which on a further alarm also retires into the rock, so that specimens can be obtained only by breaking off portions of the mass. These, when put into tubs of sea water, may be preserved for months, and the habits of the animals attentively studied. The species in question is characterized by a simple undulated tube of a whitish hue, the tentacula being varied by beautiful alternate bands of red and white. *Amphitrite vicicola* is a British species described by Montagu. The internal texture of its tube is coriaceous, but the outer coat is invariably covered by coarse sand, intermixed with fragments of shells. (See Plate CCLXXV. fig. 5.) Considerable variety exists in the form and aspect of the genus Sabella.
**Genus Teredobella**, Cuv. These, like the preceding, inhabit a tube of their own formation, but composed of coarser materials than that of the generality of Sabellae. Their body presents much fewer segments, and the head is otherwise adorned. Numerous filiform tentacula, capable of great extension, surround the mouth; and on the neck are placed the branchiae, which are not fan-shaped, but in the form of little branches.
The animals of this genus, according to Montagu, either prepare a sheath from the tenacious secretion of their own bodies, mixed with adventitious matters, or reside in prepared perforations at the bottom of the sea. Their tubes are in general so extremely fragile as to be easily destroyed, and the animals are then found lurking beneath stones, or forming a new dwelling. Some fabricate their tube in old shells or stones, to which they adhere by their entire length, while others fix a tube perpendicularly in the sand. These tubes are indeed frequently observed to obtrude several inches above the surface of the soil, and when the waters flow, the gills and other appendages are stretched forth, and seem agitated to and fro. The gills or branchial appendages are extremely sensible, of a fine blood colour, and when touched they contract so suddenly as to expel the fluid which they contain, and then they lose their sanguine hue. Many are gregarious, and so numerous, that the sea-shore is sometimes seen covered by their fragments after a storm. When their tubes are entire, but a small portion of the body is protruded, with the exception of the filiform tentacula, which they thrust about in all directions as if in search of food. The branchial appendages, just mentioned as so finely coloured during life, lose their brightness from day to day as the animals become sickly in confinement.
*T. gigantea*, Mont. the largest of the genus, measures sixteen inches in length, and occurs, though rarely, on the Devonshire coast. We here figure as an example another species, which has likewise been taken on that coast by deep dredging, viz. *T. nebulosa* of Montagu. See Plate CCLXXV. fig. 8.
**Genus Amphitrite**, Cuv. *Pectinaria*, Lam. Recognizable by the golden coloured bristles ranged in a coronal or pectinated manner, in one or more rows, on the anterior portion of the head, where they probably serve...