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The class of Birds comprehends 930 species, which are characterized by the colours of the plumage, the forms of the feathers, the existence of wattles, spurs, and various other circumstances.
The third class, Amphibia, is composed of animals not, strictly speaking, capable of living both in air and in water, but having the power of suspending their respiration in a more arbitrary manner than others. They are arranged under four orders:—
I. Reptiles. Amphibious animals respiring through the mouth by means of lungs; and furnished with four feet.
To this order belong the tortoises, dragons, crocodiles, lizards, toads, and frogs, which are disposed into four genera, containing 83 species.
II. Serpentes, Serpents. Respiring through the mouth by means of lungs; destitute of feet, fins, and ears.
There are six genera, and 132 species.
III. Meantes, Gliders. Respiring by means of gills and lungs; furnished with feet and claws.
There is only one species, the lizard-syren of Carolina.
IV. Nantes, Swimming Amphibia. Respiring at will by means of gills and lungs: the rays of the fins cartilaginous.
These animals, of which 76 species are enumerated, are referred to fourteen genera,—the lamprey, ray or skate, shark, chimæra, frog-fish, sturgeon, lump-fish, oldwife-fish, bonyskin-fish, sun-fish, porcupine-fish, trumpet-fish, pipe-fish, and dragon-fish.[Pg 286]
The number of species described as belonging to this class is 292. The specific characters are derived from various circumstances connected with the external conformation; in the tortoises, from the shell and feet; in the snakes, from the number of the abdominal and caudal plates; in the swimming amphibia, or, as they are now more properly called, the cartilaginous fishes, from the form of the body, the differences of the fins, and other circumstances.
The fourth class, that of Fishes, contains four orders, founded upon the relative position of the fins, which are compared to the feet of other animals. Thus, the ventral fins may be placed before, beneath, or behind the pectoral, or they may be wanting.
I. Apodes, Apodal or Footless. Fishes destitute of ventral fins; such as the eel, the wolf-fish, and the sword-fish.
II. Jugulares, Jugular. Fishes having the ventral fins placed before the pectoral; as the dragonet, weever, cod, haddock, and coal-fish.
III. Thoracici, Thoracic. Fishes having the ventral fins placed under the pectoral; as the goby, bull-head, holibut, gilt-head, perch, mackerel, &c.
IV. Abdominales, Abdominal. Fishes having the ventral fins placed on the abdomen behind the pectoral fins; as in the salmon, trout, pike, mullet, and herring.
In this class there are 47 genera, and 400 species. The specific characters are taken from the number of rays in the fins, the form of the tail, the cirri or filaments at the mouth, the colouring of the body, the form of the scales, and other circumstances.[Pg 287]
The fifth class, that in which the Insects are included, comprehends 86 genera, disposed into seven orders, which are founded on the number and texture of the wings.
I. Coleoptera, or Hard-winged Insects. Insects having the wings covered by two crustaceous cases. This order is the most extensive, including 30 genera, and 893 species. It includes all the insects commonly known by the name of beetles.
II. Hemiptera, or Half-winged Insects, having the shells or cases semicrustaceous, not divided by a straight line as in the coleoptera, but overlapping each other at the margin; the beak curved inwards; 12 genera, 353 species. The cockroach, cricket, locust, and cochineal-insect, are examples.
III. Lepidoptera, or Scaly-winged Insects, having four wings, which are covered with imbricated scales; the tongue spiral and coiled up, the body hairy. In this order there are only 3 genera, Papilio, Sphinx, and Phalæna, the butterflies and moths; but the species are 780.
IV. Neuroptera, or Net-winged Insects, with four naked, transparent, or reticulated wings; the tail generally destitute of a sting. There are 7 genera, and 83 species, among which are the dragon-fly, the may-fly, and the scorpion-fly.
V. Hymenoptera, or Thin-winged Insects, with four naked membranous wings; some species, however, being wingless. The females have the tail armed with a sting. This order contains 10 genera, and 313 species, of which may be mentioned as examples, the wasp, bee, ichneumon-fly, and ant.
VI. Diptera, or Two-winged Insects, having only two wings, and being furnished with a balance or club behind each wing. There are 10 genera, and 262 species, among which are the common house-fly, the flesh-fly, and the gnat.[Pg 288]
VII. Aptera, Wingless. Insects destitute of wings in both sexes. They are arranged under 14 genera, and consist of 300 species. In this order there are three divisions: some have six feet, as the flea, the louse, and the white ant; others have from 8 to 14 feet, as the spider, scorpion, crab, and lobster; while others have a still greater number, as the centipede.
The generic characters are derived from the antennæ, the jaws, the head, the thorax, the wings, the elytra or wing-covers; and the specific, from the colours and other circumstances. The number of species is 2984.
The sixth class, that of Vermes or Worms, is a very heterogeneous one, and to later authors has supplied materials for several classes. Linnæus divides it into five orders:
I. Intestina, Intestinal Animals: simple, naked, and destitute of limbs: for example, the earth-worm, the guinea-worm, the leech, and the ascaris: 7 genera, 24 species.
II. Mollusca. Simple, naked animals, furnished with limbs: the slug, the sea-mouse, the sea-anemone, the cuttlefish, the sea-nettle, the star-fish, and the sea-urchin: 18 genera, 110 species.
III. Testacea, Shell-fish. Soft, simple animals, covered with a shell which is usually calcareous. This order includes 36 genera, and 814 species. It is divided into three groups, the multivalve shells, or those which consist of several pieces; the bivalve, of two pieces; and the univalve, or those of one piece only.
IV. Lithophyta. Compound animals, affixed to, and fabricating a fixed calcareous base, called coral. There are 59 species, which are referred to 4 genera, the tubipores, madrepores, millepores, and cellepores.
V. Zoophyta. Compound animals, sending forth processes[Pg 289] resembling flowers, and springing from a vegetating stem. This order contains 15 genera, among which are the red coral, the sea-fan, the sponge, coralline, &c. The number of species is 156.
