REPTILES. 129 



e^. A sharp tooth on either side of the notcli at 



the syiiiphvsis of* the upper jaws. Carapace 



without round, bright orange spots, 



Chrysemys. 



f^ Vertebral and costal scutes unicolored 



except for a Yelh)W margin. A rela- 



tiveh' small plastral blotch along the 



median line C. cinerea, p. 141. 



f^. Vertebral and costal scutes marked with 

 irregular pale-yellow lines. A large 

 blotch covering most of the plast- 

 ron C. 'belliiy p. 113. 



e-. Xo teeth bounding the notch at the anterior 

 end of the upper jaws. Carapace marked 

 with numerous, round, bright orange spots. 



Clemmys guttata, p. 147. 



d'. Carapace with a strong median keel 



Graptemys geographica, p. 150. 



C". Plastron with a transverse hinge, and movablv at- 

 tached to the carapace, 

 d^. Upper jaw notched in front. Carapace long and 



depressed Emydoidea 'blandingii, p. 153. 



d-. Upper jaw produced downward at the symphysis 

 to form a hook. Carapace short and high .... 

 Terrapene Carolina, p. 155. 



PLATYPELTIS SPINIFEKA (LeSueur). 



SOFT-SHELLED TURTLE. 

 (Pis. VII, XI a) 



Aspidonectes sjrinifer. Smith, 1S70, 7. Clark, 1902, 103; 1005, 110. 



Miles, 1861, 233. Agassiz, 1857, 404-405. 

 Trionyx spin if ems, Thompson, 1911, 107. 



Description : Body broad and very fiat. Carapace and plastron 

 not covered with epidermal pUites, but by a soft and leathery skin, 

 the margins of the carapace bending freely at the edges. Head 

 tapering to the snout which is much ])roduced and flexible. Nos- 

 trils separated by a septum, and each willi a ]>ai>illa projecting into 

 it from the septum. A Ioav obtuse keel along the middle of the 

 back. A series of spines along the anterior edge of the carapace, 

 in the adults; the entire upper surface of the carapace covered 

 with small tubercles. Feet broad and fully Avebbed. 

 17 



