20 INTRODUCTION. 



3, Reptiles. 



4. Fishes. 



The class of Mammals is subdivided into three orders : 

 a Beasts of prey, ( Carnivora.) 

 h Those which feed on vegetables, (Herhivora.) 

 c. Animals of the whale kind, [Cetaceans.) 



The class of Birds is divided into four orders, namely, 

 a. Perching Birds, (Insessores.) 

 h. 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 exUnct, (Rhizodoiits.) 

 h. Lizards, {Lacertians.) 



c. Snakes, (Ophidians.) 



d. Turtles, (CheloniaJis.) 



e. Frogs and Salamanders, {Batrachians.) 



The class of Fishes is divided into four orders : 



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



(Ganoids,) fig. 157, c. 

 h. Those with the skin like shagreen, as the sharks and 



skates, [Placoids.) 

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



and usually w^ith some bony rays to the fins, as the 



perch, (Clenoids.) 



