INTRODUCTION. XXI 



The Animal Kingdom consists of four great divisions which 

 we call DEPARTMENTS, namely, 



I. The department of Vertebrata. 

 II. The department of Articulata. 



III. The department of Mollusca. 



IV. The department of Radiata. 



I. The department of VERTEBRATA. includes all animals 

 which have an internal skeleton, with a back-bone for its axis. 

 It is divided into four classes. 



1 . Mammals (animals which nurse their young) . 



2. Birds. 



3. Reptiles. 



4. Fishes. 



The class of MAMMALS is subdivided into three orders. 



a. Beasts of prey (Carnivord). 



b. Those which feed on vegetables (Herbivord). 



c. Animals of the whale kind (Cetaceans). 



The class of BIRDS is divided into four orders. 



a. Birds of prey (Incessores) . 



b. Climbers (Scansores). 



c. Waders (Grallatores) . 



d. Swimmers (Natatores). 



The class of REPTILES is divided into five orders. 



a. Large reptiles with hollow teeth, most of which are 



now extinct (RhizodotUs\ 



b. Lizards (Lacertans). 



c. Snakes (Ophidians). 



d. Turtles (Cheionians). 



e. Frogs (Batrachians). 



The class of FISHES is divided into four orders : 



a. Those with enamelled scales, like the gar-pike 



Lepidosteus (Ganoids]. 



b. Those with the skin like shagreen, as the sharks 



and skates (Placoids). 



c. Those which have the edge of the scales toothed, 



and usually with some bony rays to the fins, as the 

 perch (Ctenoids). 



d. Those whose scales are entire, and whose fin ravs are 



v 



soft, like the salmon (Cycloids). 



