46 Introduction 



1. Cyclostomata. Round-mouthed fish with poorly developed backbone. Ex- 

 ample : lamprey eel. 



2. Chondrichthycs. Cartilage-boned fish with a true mouth. Example: 

 shark. 



3. Osteichthycs. Fish which usually possess bony skeletons. Examples : sun- 

 fish, perch, trout. 



4. Amfihibia. Animals which usually possess legs, skin mostly without scales, 

 moist, and soft. Typically with the larval stage in water. Examples : frog, sala- 

 mander, toad. 



5. Reptilia. Skin with scales, eggs with well-developed shell. Examples : 

 snake, crocodile, alligator, turtle, lizard. 



6. Avcs. Animals with feathers, usually able to fly, with well-developed egg. 

 Example : the birds. 



7. Mammalia. Animals with hair, mammary glands for nourishment of the 

 young. Examples : man, rat, cow, horse. 



