CTASSIFICATION 37 



Vertehrata or Craniata. 

 Class, Cyclostomata. 

 Primitive, aquatic forms without jaws and paired 

 appendages, and with circular mouths, e.g., 

 Lampreys, etc. (Fig. 1 E). 

 Class, Pisces. 

 Aquatic forms with paired appendages, true 

 jaws, and with scales in the skin, e.g., the 

 Fishes. 



Sub-class, Elasmohranchii. 



Fishes with cartilaginous skeletons, e.g., 

 Sharks, Skates, etc. (Fig. 1 D). 

 Sub-class, Teleostomi. 



Fishes with bony skeletons, e.g., the more 

 famihar fresh-water fishes (Fig. IC). 

 Class, Amphibia. 



Semi-terrestrial and aquatic forms with soft 

 moist skin and tadpole stage in development, 

 e.g., Salamanders, Frogs, Toads, etc. (Fig. 

 1 B). 

 Class, Kept ilia. 



Terrestrial forms with scaly bodies, well 

 developed lungs, and other adaptations for 

 terrestrial life, e.g.. Lizards, Alhgators, Tur- 

 tles, Snakes, etc. (Fig. 1 A). 

 Class, Aves. 



Terrestrial forms adapted for flight, covered 

 with feathers, e.g., Birds (Fig. 2). 

 Class, Mammalia. 



Animals with hair and mammary glands, and 

 in most cases giving birth to well-developed 

 young, e.g., Mammals (Fig. 3). 



