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. TRIONYCHOIDE A. - - 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. Vertebras biconcave, often containing 

 remains of the notochord; immovable quadrate bone; 

 parietal organ present. Example: Sphenodon (Fig. 

 45) 



Orders. Crocodilini. -- CROCODILES, ALLIGATORS, GA VIALS, 

 and CAIMANS. Reptiles with proccelous vertebras; 

 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^:. 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; vertebra 

 usually proccelous; quadrate bones movable. 

 Suborder i. RHIPTOGLOSSI. - - CHAMELEONS. - - SQUAMATA 

 with body laterally compressed; tail prehensile; 

 tongue vermiform, projectile; well-developed limbs; 



