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, Emydura. 



Superfamily 4. TRIONYCHOIDEA. TESTUDINATA with 

 soft, leathery skin, without horny shields. 



Family i. CARETTOCHELYDID.E. TRIONYCHOIDEA with 

 paddle-shaped limbs; neck not retractile. Example: 

 Carettochelys (one species C. insculpta from New 

 Guinea.) 



Family 2 . TRIONYCHID^E. SOFT-SHELLED TURTLES. TRI- 

 ONYCHOIDEA with digits broadly 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 vertebrae; 



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 i. 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 i. RHIPTOGLOSSI. -- CHAMELEONS. SQUAMATA 



with body laterally compressed; tail prehensile; 



tongue vermiform, projectile; well-developed limbs; 



