52 NORTH AMERICAN BATRACHIA AND REPTILIA. 



Genus Amyda, Ag. 



98. A. mutica, (Les.) Ag. Fresh-water Leather Turtle. 

 Back depressed; no spines on anterior margin of carapace, and 

 no tubercles on back. Color above, in adult, nearly plain olive; 

 in young, more or less spotted with black; below whitish, with- 

 out spots, Korth of the Ohio river, in tributaries to the Mis- 

 sissippi and St. Lawrence. 



Genus Aspidonectes, Wag. 

 a. Lower surface of body and under part of feet white. 



99. A. ferox^ Schw. Soft-shelled Turtle. Tubercles on 

 shield in male larger than in female; in the young, two or three 

 concentric black lines, separating the pale margin from the light 

 brown colored back, which is studded with black dots and ocel- 

 lated spots, becoming blotched in the adult. Georgia to Western 

 Louisiana. 



h. Lower surface and under parts of feet spotted with 

 black. 



100. A. spinifer^ Les. Common Soft-shelled Turtle. A. 

 blunt median keel, sloping uniformly on the sides; in the young, 

 a single black line about the edge of the carapace; shield olive- 

 brown, with dark spots; spines less prominent in males than in 

 females. JSTorth of the Ohio river, in tributaries of the Missis- 

 sippi and St. Lawrence. 



101. A. nuchalis^ Ag. Agassiz's Soft-shelled Turtle. 

 Marked depressions on either side of the blunt median keel, 

 which has a triangular dilation in front; spines and tubercles 

 prominent in the male. Cumberland and Upper Tennessee 

 rivers. 



102. A. asper^ Ag. Tubercles large and coarse, behind 

 supported by prominent bony warts on the osseous plates; in 

 the young, two or three black lines around the posterior part of 

 the carapace. Tributaries of the Lower Mississippi. 



Family CHELYDRID^. 



Head narrow about the nose and eyes, broad behind; feet 

 strong, and toes with long, strong claws; web small. 



a. Eyes lateral and distant; alveolar plate very broad; 

 strong pointed projection at the symphysis of the 

 jaws; three scales on each side between costal and 

 marginal rows Macrochelys. 



