DIVISION ? THE ANIMAL KINGDOM. 301 



IV. MOLLOSCA, or soft bodied animals, destitute of bones, uu- 

 'der this head are embraced the fossil shells. 



1. BIVALVES, or consisting of two pieces like the oyster and clam. 



2. UNIVALVES, or consisting of one shell like the snail and peri- 

 winkle; these latter are the true molluscs, and are of a 

 higher degree of organization than the former, possessing 

 a head and eyes, of which the former are destitute. 



3. CHAMBERED shells like the nautilus, including both the tes- 

 taceous or shell covered genera, and naked molluscs as the 

 cuttle-fish. 



4. CIRRIPEDIA., or hairy-footed animals, like the barnacle. 



V. ARTJCULATA, or jointed animals, comprising, 



1. ANNELATA, or ring ed animals, like the red blooded worm. 



2. INSECTA, or insects, i. e. having the body nearly divided in 

 two, like the wasp and fly. 



3. ARACHNIDA, or spiders. 



4. CRUSTACEA, having a crustaceans skin like crabs and lobsters. 



VI. VERTEBRATA, or animals having a spinal column or back- 

 bone, subdivided into, 



1. PISCES, or fishes. 



2. REPTILIA, or reptiles. 



3. AVES, or birds. 



4. MAMMALIA, or animals giving suck. 



The animal kingdom is divided into the above great classes-, 

 "and these are subdivided into a vast number of species, each being 

 characterized by some peculiar and distinguishing mark. The 

 expert anatomist can often from the mere inspection of a tooth, 

 or a claw, determine the character and habits of an animal. Of- 

 tentimes this, or even a foot-print in the sand, is all that remains 

 of some now extinct creature, yet by analogy, instituting a rigid 

 and close comparison with existing species of the same gen- 

 era, the peculiarities are distinctly made out, and many remarka- 

 ble facts are brought to light. We now proceed to consider the 

 probable condition of our planet during the stages of existence 

 before enumerated. 



