Orders of Mammalia
The first class, or Mammalia, consists of such animals as produce living offspring, and nourish their young ones with milk supplied from their own bodies; and it comprises both the quadrupeds and the cetacea.
This class was divided by Linnæus into seven Orders: viz. primates, bruta, feræ, glires, pecora, belluæ, and cetacea (this order was called Cete by Linnæus) or whales. The characteristics of these were founded, for the most part, on the number and arrangement of the teeth; and on the form and construction of the feet, or of those parts in the seals, manati, and cetacea, which supply the place of feet:
I. Primates.—Having the upper front teeth, generally four in number, wedge-shaped, and parallel; and two teats situated on the breast, as the apes and monkeys.
II. Bruta.—Having no front teeth in either jaw; and the feet armed with strong hoof-like nails, as the elephant.
III. Feræ.—Having in general six front teeth in each jaw; a single canine tooth on each side in both jaws; and the grinders with conic projections, as the dogs and cats.
IV. Glires.—Having in each jaw two long projecting front teeth, which stand close together; and no canine teeth in either jaw, as the rats and mice.
V. Pecora.—Having no front teeth in the upper jaw; six or eight in the lower jaw, situated at a considerable distance from the grinders; and the feet with hoofs, as cattle and sheep.
VI. Belluæ.—Having blunt wedge-shaped front teeth in both jaws; and the feet with hoofs, as horses.
VII. Cetacea.—Having spiracles or breathing-holes on the head; fins instead of fore feet; and a tail flattened horizontally, instead of hind feet. This order consists of the narvals, whales, cachalots, and dolphins.