Natural History, is that science which not only gives compleat descriptions of natural productions in general, but also teaches the method of arranging them into Classes, Orders, Genera, and Species. This definition includes Zoology, Botany, Mineralogy, &c. But, in a work of this kind, we thought it would be easier, and more advantageous to the reader, to treat these branches of natural history separately under their respective names. See Botany, &c. Under the title of Natural History, therefore, we shall confine ourselves to Zoology, or that part of it which relates to Animals. It is likewise necessary to mention in this place, that we have given the descriptions and characters of animals under their proper names. The scientific part of the subject, therefore, or the method of investigating the genera or species of animals, by means of natural or artificial arrangement, only remains to be explained.

In order to abridge the study of zoology, many methods of reducing animals to classes, genera, and species, have been invented. But, as that of Linnaeus is undoubtedly the best, the most extensive, and the least understood, we shall give a brief account of it.

Linnaeus divides the whole animal kingdom into 6 classes. The characters of these 6 classes are taken from the internal structure of animals, in the following manner:

Class I. MAMMALIA, includes all animals that suckle their young. The characters of this class are these:—The heart has two ventricles and two auricles; the blood is red and warm; and the animals belonging to it are viviparous.

Class II. AVES, or Birds.—The characters are the same with those of Class I., excepting that the animals belonging to it are oviparous.

Class III. AMPHIBIA, or Amphibious Animals.—The heart has but one ventricle and one auricle; the blood is red and cold; and the animals belonging to this class have the command of their lungs, so that the intervals between inspiration and expiration are in some measure voluntary.

Class IV. PISCES, or Fishes.—The heart has the same structure, and the blood the same qualities with those of the Amphibia; but the animals belonging to this class are easily distinguished from the Amphibia, by having no such voluntary command of their lungs, and by having external branchiae or gills.

Class V. INSECTA, or Insects.—The heart has one ventricle, but no auricle; the blood is cold and white; and the animals are furnished with antennæ, or feelers.

Class VI. VERMES, or Worms.—The characters are the same with those of Class V., only the animals have no antennæ, and are furnished with tentacula.

The First Class, MAMMALIA, is subdivided into 7 Orders; the characters of which are taken from the number, structure, and situation of the Teeth.

Order I. The Primates, have 4 incisors, or fore-teeth, in each jaw, and one dog-tooth. N.B. By one dog-tooth, Linnaeus means one on each side of the fore-teeth in both jaws.—This order includes 4 genera, viz. Homo, Simia, Lemur, Vespertilio. See these articles.

Order II. The Bovidae, have no fore-teeth in either jaw.—This order includes 6 genera, viz. Elephas, Trichechus, Bradypus, Myrmecophaga, Manis, Dasyurus. See these articles.

Order III. The Feræ, have, for the most part, 6 conical fore-teeth in each jaw.—This order includes 10 genera, viz. Phoca, Canis, Felis, Viverra, Mustela, Ursus, Didelphis, Talpa, Sorex, Erinaceus. See these articles.

Order IV. The Gliræ, have 2 fore-teeth in each jaw, and no dog-teeth.—This order includes 6 genera, viz. Hyltrix, Lepus, Castror, Mus, Sciurus, Noctilio. See these articles.

Order V. The Pecora, have no fore teeth in the upper jaw, but 6 or 8 in the under-jaw.—This order includes 6 genera, viz. Camelus, Moschus, Cervus, Capra, Ovis, Bos. See these articles.

Order VI. The Belluæ, have obtuse fore-teeth in each jaw.—This order includes 4 genera, viz. Equus, Hippopotamus, Sus, Rhinoceros. See these articles.

Order VII. The Cete, or whale kind, have no uniform character in their teeth, being very different in the different genera; but are sufficiently distinguished from the other orders of Mammalia, by living in the ocean, having pectoral fins, and a fistula or spiraculum upon the head.—This order includes 4 genera, viz. Monodon, Balena, Physeter, Delphinus. See these articles.

The generic characters of the Mammalia are, like those of the orders, almost entirely taken from the Teeth, excepting excepting the Vespertilio, which, besides the character of the order derived from the teeth, has this further mark, that there is a membrane attached to the feet and sides, by means of which the creature is enabled to fly;—the Hylirix, whose body is covered with sharp spines;—and the whole order of Pecora, whose genera, besides the characters taken from the teeth, are distinguished into those which have horns, those which have no horns, and by peculiarities in the horns themselves.

The specific characters are very various, being taken from any part of the body which possesses a peculiar uniform mark of distinction. As examples of these characters are to be found under the proper name of each genus, it is unnecessary to say anything further concerning them in this place.

The Second Class, AVES, is subdivided into six Orders, the characters of which are taken chiefly from the structure of the Bill.

Order I. The Accipitres, have a hooked bill, the superior mandible, near the base, being extended on each side beyond the inferior; and in some, the superior mandible is armed with teeth.—This order includes 4 species, viz. Vultur, Falco, Strix, Lanius. See these articles.

Order II. The Picæ, have a convex, compressed bill, resembling a knife.—This order contains 22 genera, viz. Buphaga, Certhia, Corvus, Cuculus, &c. See these articles.

Order III. The Anseres, have an obtuse bill, gibbous at the base, broadest at the point, covered with a smooth skin, and furnished with teeth: The tongue is fleshy; and the toes are palmated, or webbed.—This order includes 12 genera, viz. Alca, Anas, Columbus, Diomedia, &c. See these articles.

Order IV. The Grallæ, have a long, obtuse, and somewhat cylindrical bill: The tongue is undivided, and fleshy; and the thighs are naked.—This order contains 18 genera, viz. Ardea, Fulica, Tringa, Charadrius, &c. See these articles.

Order V. The Gallinæ, have a convex bill; the superior mandible is vaulted over the inferior, and the margin of the superior mandible folds over the inferior one: The nostrils are half covered with a convex cartilaginous membrane: The rectrices, or principal quill-feathers of the tail, are always more than twelve in number; and the feet are divided, but connected at the inmost joint.—This order contains 7 genera, viz. Didus, Phasianus, Meleagris, Pavo, &c. See these articles.

Order VI. The Passeres, have a conical sharp-pointed bill; and the nostrils are oval, wide, and naked.—This order contains 15 genera, viz. Caprimulgus, Alauda, Columba, &c. See these articles.

The generic characters of this class are taken from peculiarities in the bill, the nostrils, the tongue, the feet, the feathers, the face, the figure of the body, &c.

The characters which serve to distinguish the species are very various: For example, the colour of particular feathers or parts of feathers; crests of feathers on the head, disposed in different manners; the colour of the cere or wax; the colour of the feet; the shape and length of the tail; the number, situation, &c. of the toes; the colour and figure of the bill; &c.

The Third Class, AMPHIBIA, is divided into four Orders.

Order I. The Reptiles, have legs, and breathe by the mouth.—This order contains 4 genera, viz. Testudo, Draco, Lacerta, Rana. See these articles.

Order II. The Serpentes, have no legs, and breathe by the mouth.—This order contains 6 genera, viz. Crotalus, Boa, Coluber, Anguis, Amphibrama, Cecilia. See these articles.

Order III. The Nantes, are furnished with lungs, and at the same time breathe by lateral gills; and the rays of their fins are cartilaginous.—This order contains 14 genera, viz. Accipenser, Balistes, &c. See these articles.

Order IV. The Meantæ, have both lungs and gills; and the feet are furnished with toes and claws.—This order contains but one genus, viz. the Siren. See Siren.

The generic characters of this class are taken from the general figure of the body; from their having tails or no tails; being covered with a shell; having teeth or no teeth in the mouth; being furnished with wings; having covered or naked bodies; from the number, situation, and figure of the scuta and scales; from the number and situation of the spiracula; from the situation of the mouth, &c.

The specific characters are so very various, that it would be superfluous to enumerate them.

The Fourth Class, PISCES, is subdivided into four Orders, the characters of which are taken from the situation of the belly-fins.

Order I. The Apodes, have no belly-fins.—This order contains 8 genera, viz. Ammodytes, Anarhichas, Muræna, &c. See these articles.

Order II. The Jugulares, have the belly-fins placed before the pectoral fins.—This order includes 5 genera, viz. Callionymus, Blennius, Gadus, &c. See these articles.

Order III. The Thoracici, have the belly-fins placed under the pectoral fins.—This order comprehends 17 genera, viz. Gabius, Labrus, Sparus, &c. See these articles.

Order IV. The Abdominales, have the belly-fins placed behind the pectoral fins. This order contains 17 genera, viz. Fistularia, Esox, Clupea, Cyprinus, &c. See these articles.

The generic characters of this class are taken from peculiarities in the head, the mouth, the teeth, the nostrils, the rays in the membrane of the gills, the eyes, the general figure of the body, the figure of the tail, the situation of the spiracula, &c.

The specific characters are taken from peculiarities in all the parts above enumerated, and many others. The Fifth Class, INSECTA, is subdivided into 7 Orders, the characters of which are taken from the wings.

Order I. The Coleoptera, have four wings, the two superior ones being crustaceous, and furnished with a straight future.—This order comprehends 40 genera, viz. Attelabus, Scorabæus, Coccinella, Meloe, &c. See these articles.

Order II. The Hemiptera, have four wings, the two superior ones being semicrustaceous, and incumbent, i.e. the interior edges lie above one another.—This order includes 12 genera, viz. Blatta, Gryllus, Cicada, &c. See these articles.

Order III. The Lepidoptera, have four wings, all of them imbricated with scales.—This order contains 3 genera, viz. Papilio, Sphinx, Phalæna. See these articles.

Order IV. The Neuroptera, have four wings interwoven with veins, like a piece of network, and no ring in the anus.—This order includes 7 genera, viz. Libella, Ephemera, Hemerobius, &c. See these articles.

Order V. The Hymenoptera, have the same characters with the former, only the anus is armed with a ring. But this mark is peculiar to the females and neuters; for the males have no ring.—This order comprehends 10 genera, viz. Apis, Formica, Vespa, &c. See these articles.

Order VI. The Diptera have two wings, and two clavated halteres or balances behind each wing.—This order contains 10 genera, viz. Combylius, Afilus, Tipala, &c. See these articles.

Order VII. The Aptera, have no wings. This order contains 14 species, viz. Acarus, Aranea, Pediculus, &c. See these articles.