REPTILES 249 



G. agassizii (Cooper). Similar to G. polyphemus; no enlarged 

 scales on the inner surface of the fore arm: southwestern Arizona and 

 southeastern Cahfornia. 



G. hcrlandieri (Agassiz). Shell globular, being very broad and 

 high; carapace brown and 150 mm. long, 136 mm. wide and 80 mm. 

 high; plastron yellow: deserts of southern Arizona, Nevada and 

 California. 



Family 4. Trionychidae. — The soft-shell turtles. Large turtles with 

 a flat, circular shell which is covered with a leathery skin and not with 

 horny plates or scales; ossification of the carapace not complete; neck 

 very long; head pointed, ending in a flexible proboscis-like snout; 

 jaws powerful, with fleshy Hps; feet webbed; toes 5-5 ; claws t^-t^ : about 30 

 species, in both hemispheres, 4 in the United States; savage, active 

 turtles, aquatic and carnivorous, valued for food; eggs spherical. It 

 has been demonstrated that these turtles can remain under water 

 several hours at a time, and that they have true water respiration when 

 submerged, taking in water into the mouth and expelling it regularly 

 about 16 times a minute. 



Amyda Oken. With the characters of the family: 4 United States 

 species. 



Key to the Species of Amyda 



ai Fore part of carapace smooth A. miitica. 



ao Fore part of carapace with conical tubercles. 



bi Light stripes on head unite between the eyes A. emoryi. 



hi Light stripes on head unite at end of the snout A. spinifer. 



bs Light stripes on head unite in front of the orbits .4. ferox. 



A. mutica (LeSueur). Body brown in color, irregularly blotched, 

 being spotted in the young; whitish below; length of carapace 170 

 mm.; width 160 mm. : central and northern tributaries of the Mississippi; 

 tributaries of the Great Lakes and St. Lawrence; not so common as 

 .4. spinifer. 



A. emoryi (Agassiz). Similar to A. spinifer: Texas and into 

 southern Oklahoma and Arkansas. 



A. spinifer (LeSueur). Soft-shell turtle (Fig. 138). Body olive 

 brown in color, with numerous round dark spots, each margined 

 with black in young animals; head and neck olive, with stripes; tuber- 

 cles on forward edge of carapace larger in the female than in the male; 

 plastron white; length of carapace 350 mm.; width 300 mm.: north- 

 central States; eastward to Vermont and western Pennsylvania; west- 

 ward to Colorado; southward to Kentucky; common. 



