162 REPTILES. 



X 



*** Carapace rather depressed ; plastron wide, flat, movable upon 

 the carapace and also upon a transverse hinge; anterior 

 lobe somewhat smaller than the posterior, which is emargi- 

 nate behind ; toes webbed. . . . . Emys, 4 



4:*** Carapace rather flat ; plastron wide and flat, as is also the 

 bridge connecting it to the carapace ; toes broadly webbed ; 

 hind-legs much stouter than fore-legs; larger species, deci- 

 dedly aquatic. 



f Upper jaw not notched in front ; carapace more or less strongly 

 keeled or tuberculated. . . . Malacoclemmys, 6. 



tt Upper jaw notched in front; shell not keeled in adult. 



X Horizontal alveolar surfaces of jaws not divided by a longi- 

 tudinal ridge ; stripes on neck, tail, legs, etc., bright red 

 (in our species); head with yellow lines; large plates *of 

 carapace plain ; marginal plates with bright red mark- 

 ings; a small tooth on each side of notch in upper jaw; 

 shell never keeled. • . . . . Ciiiiysemys, 5. 



XX Horizontal alveolar surfaces divided by a longitudinal 

 ridge, running paVallel with the cutting edge; stripes on 

 legs, etc., usually yellow, never bright red; large plates 

 of carapace often variegated; traces of a keel usually 



• evident, at least in the young. . . Pseudemys, 7. 



/. CISTUDO, Fleming. Box Turtles. 



1. C. Carolina^ (L.) Common Box Turtle. Colors 

 very variable, chiefly blackish variegated with yellowish; 

 N. Y. to Mo. and S. in dry woods. 



Var. triunguiSj (Ag.) Cope. Three-Toed Box Turtle. 

 Hind-feet mostly 3-toed, paler. Southern, N. to Pemi. 



2. C. ornata, Ag. Northern Box Turtle. " Shell 

 round, broad, flat, without keel, even when young." 

 Iowa and W. 



2. CHELOPUS, Rafinesque. Wood Turtles. 



* A deep notch in upper jaw, with a lengthened tooth on Ccich 

 side of it ; lower jaw strongly arched upwards. {Calemys^ Ag.) 



