112 UNIVERSITY OF COLORADO STUDIES 



a weight of thirty pounds or more. The soft-shelled turtles are 

 vigorous, active animals and when disturbed snap much like the true 

 snapping turtles. A single genus of this family is represented in 

 Colorado. 



Genus TRIONYX Geoffroy 



Trionyx Geoffroy, Annates Mus. Paris, p. 84, 1809. 



Plastron poorly developed posteriorly; hind limbs and tail free; 

 digits, 5-5; claws, 3-3; range, that of the family. One species known 

 from Colorado. 



Trionyx spiniferus LeSueur 



Spiny Soft-Shelled Turtle 



Trionyx spiniferus LeSueur, Mem. Mus. Hist. Nat. Paris, p. 258, 1827. 



Dorsal surface covered with tiny elevations; anterior margin of 

 the carapace, especially that of adult females, with numerous small 

 conical tubercles (these are usually wanting or very small in young 

 specimens) ; nostrils at the tip of the elongate snout, crescent-shaped 

 and each with a small papilla projecting into it from the septum; 

 tail of the female scarcely projecting beyond the margin of the cara- 

 pace, that of the male projecting beyond the carapace almost the 

 length of the head; digits, 5-5; claws, 3-3; size medium, length of 

 the carapace up to fifteen inches. 



Dorsal color olive, green or brownish, with a margin of lighter 

 color separated from the rest of the ground color by a narrow black 

 line; young specimens with twenty or more rounded spots of dark 

 color, margined with black, these spots becoming more indistinct as 

 the animal grows older ; ventral parts white or yellowish; under parts 

 of the legs and the ventral margin of the carapace more or less mottled 

 with black. 



The flesh of this turtle is of very good quality and the turtle is 

 much sought after in regions where it is at all abundant. It ranges 

 from Maine to the Rocky Mountains, and south to Mexico. It is 

 most abundant in the north central states. 



Colorado specimens. — University Museum: Evans, July 4, 1908 (about 

 250 mm.), J. Henderson; Stale Teachers' College Museum: Cache la Poudre, South 

 Platte River and Greeley, A. E. Beardsley. 



