AMPHIBIA AND REPTILIA OF COLORADO III 



Sistrurus catenatus edwardsii (Baird and Girard) 

 Edwards' Massasauga 



Crotalophorus edwardsii Baird and Girard, Cat. N. Am. Rept., Pt. I, p. 15, 

 1850. 



Sistrurus catenatus edwardsii Cope, Rept. U.S. Nat. Mus., p. 1144, 1898. 



General color and pattern much the same as Crolalus confluentus. 

 Range, Colorado south into Mexico. 



Colorado specimen. — Stale Teachers' College Museum: Baca County, A. E. 

 Beardsley. 



Order TESTUDINATJ 

 The Turtles 

 Four families of Turtles are known from Colorado, although but 

 six species have been reported. The families may be distinguished by 

 the following key. 



a. Body much depressed; carapace and plastron poorly ossified and covered 

 with a thick leathery skin; snout long and tubular. 



Family Trionychidae (page in). 

 aa. Body elevated at least in the mid-dorsal region; carapace and plastron 

 well ossified. 

 b. Tail long, with a mid-dorsal series of elevated bony tubercles; plastron 



small, with 9 plates Family Chelydridae (page 113). 



bb. Tail short, without a mid-dorsal row of tubercles; plastron large. 



c. Plastron with 7, 9 or 11 plates; 23 marginal plates on the carapace. 

 Family Kinosternidae (page 114). 

 cc. Plastron with 12 plates; 25 marginal plates. 



Family Testudinidae (page 115). 



Family Trionychidae 

 The Soft-Shelled Turtles 

 Turtles of this family are found in the fresh waters of America, 

 Asia, including Japan, and Africa. They may be recognized at once 

 by their greatly depressed bodies and the leathery covering of the 

 carapace which takes the place of external plates in the other turtles. 

 Most of the species are of small or moderate size, but the Southern 

 Snapper, found in southern United States, T. ferox, is known to reach 



