536 COLLEGE ZOOLOGY 



Family 2. Chelydid^e. — Fresh- water Turtles. — 

 Pleurodira with neck not completely retractile within 

 the shell ; plastron of nine bones. Examples : Hydras- 

 pis, Eniydura. 

 Superfamily 4. Trionychoidea. — Testudinata with 

 soft, leathery skin, without horny shields. 



Family 1. Carettochelydid^e. — Trionychoidea with 

 paddle-shaped limbs; neck not retractile. Example: 

 Carettochelys (one species C. insculpta from New 

 Guinea.) 



Family 2 . Trion y chid.e. — Soft-shelled Turtles . — Tri- 

 onychoidea with digits brcadly webbed; head and 

 neck retractile, bending in vertical plane. Examples: 

 Trionyx (Fig. 449), Emyda. 

 Order 2. Rhynchocephalia. — One genus of New Zealand lizard- 

 like reptiles. Vertebrae biconcave, often containing 

 remains of the notochord; immovable quadrate bone; 

 parietal organ present. Example: Sphenodon (Fig. 



45°)- 

 Order 3. Crocodilini. — Crocodiles, Alligators, Ga vials, 



and Caimans. — Reptiles with proccelous vertebra;; 



nostril single, at end of snout; anterior appendages 



with five digits, posterior with four and traces of a 



fifth; anal opening a longitudinal slit. 

 Family 1. Gavialid^e. — Ga vials. — Crocodilini with 



long, slender snout. Example: Gavialis (Fig. 451). 

 Family 2. Crocodilid^e. Crocodiles, Alligators, and 



Caimans. — Crocodilini with broad, rounded snout. 



Examples: Crocodilus, Alligator, Caiman (Fig. 451). 

 Order 4. Squamata. — Chameleons, Lizards, and Snakes. — 



Reptiles usually with horny epidermal scales; vertebrae 



usually proccelous; quadrate bones movable. 

 Suborder 1. Rhiptoglossi. — Chameleons. — Squamata 



with body laterally compressed; tail prehensile; 



tongue vermiform, projectile; well-developed limbs; 



