INTRODUCTION. 



III. Division. HOMOGANGLIATA. 

 Class 1. Crustacea. Class 4. Myriapoda. 



2. Arachnida. 5. Annelida. 



3. Insecta. 



IV. Division. NEMATONEURA. 

 Class 1. Echinodermata. Class 4. Bryozoa. 



2. Epizoa. 5. Crelelmintha. 



3. Rotifera. 



V. Division. ACRITA. 



Class 1. Sterelmintha. Class 4. Polypa. 



2. Acalephse. 5. Spongia. 



3. Polygastrica. 



After these greater divisions are distributed into classes, 

 which will be presently described, there are several smaller 

 divisions also, of which it will be useful and necessary to give 

 some account. 



CLASSES are subdivided into a greater or less number of OR- 

 DERS, and these are distinguished by some important, clear, 

 and remarkable peculiarities of conformation and structure, 

 which are common to all the animals included under each 

 of them. Thus in the class Mammalia, the order Quadru- 

 mana includes those animals which have hands upon all four 

 of their extremities, such as monkeys and apes ; the order 

 Ruminantia, those which ruminate or chew the cud; the or- 

 der Carnivora, those adapted to feed principally on animal 

 food. In the other classes the divisions are of a similar 

 kind. 



ORDERS are subdivided into GENERA. These comprehend 

 animals which have a general resemblance to each other, a 

 kind of family likeness. Thus the genus Felis includes all 

 those of the cat kind, and these animals, although differing 

 one from another very much in size and color, have yet a 

 close resemblance in their general form, figure, character, and 

 habits of life. The genus Canis includes those of the dog 

 kind, the wolf, the fox, the jackal, and the domestic dog, of 

 which the same remark may be made. Thus, too, the horse, 

 the ass, and the zebra are of the same genus, Equus, on 

 account of their obvious general similarity. 



Again, GENERA are made up of .SPECIES. Each distinct 

 sort of animal constitutes a species, and they are known from 



