240 VERTEBRATE ANIMALS OF THE UNITED STATES 



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

 about 1 6 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 J . mutica. 



ao Fore part of carapace with conical tubercles. 



bi Light stripes on head unite between the eyes 1. emoryi. 



bo Light stripes on head unite at end of the snout A. spinifera. 



hi Light stripes on head unite in front of the orbits 1. ferox. 



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

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



Fig. 138. — Amyda spinifera {from Fowler). 



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

 Brazos and Colorado rivers; not so common as A. spinifera. 



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

 southern Oklahoma and Arkansas. 



A. spinifera (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. : Mississippi 

 and St. Lawrence rivers and Great Lakes and their tributaries; common. 



A . ferox (Schneider) . Large turtles similar to A . spinifera, but plain 

 brown in color in the adult; young spotted or blotched; length of cara- 

 pace 450 mm.; width 370 mm.; weight 13 kilos: southern States from 

 South Carolina to Louisiana; common. 



