Species of North American Tortoises. 123 



ral and vertebral plates, being only distinguished from them by 

 the sutures. Sternum small, narrow, very deeply emarginate 

 behind, sometimes imperfectly jointed at the pectoral plates, 

 dirty yellowish, each plate often bordered with dusky ; scapu- 

 lar plate single, very small, subtriangular, irregular in shape ; 

 brachial plates projecting beyond the pectoral at the exterior 

 and posterior angle, small, irregular, sometimes triangular, 

 sometimes four-sided, frequently one of them triangular, the 

 other four-sided ; ihe abdominal the largest, the femoral ap- 

 proacliing to a triangular form ; supplementary plates of the 

 wings irregular, interposed between the wings and the margi- 

 nal plates, the posterior the largest. Skin dusky, head rather 

 pointed, jaws inclining to yellow, an interrupted yellow line 

 proceeds^rom the nose above the eye along the side of the 

 neck, and another similar one from the bottom of the eye to- 

 wards the throat ; throat and sides of the neck granulate or 

 papillous ; chin furnished with several small warts. Legs 

 naked ; forelegs with tliree folds or large scales on the fore 

 part, and somewhat granulate, sometimes with a few small 

 scales beneath at the insertion of the feet ; hind legs granulate 

 beneath and with a few small scales at the base of the feet. 

 Eyes black, pupil surrounded by a yellow ring. Tail naked, 

 simple, furnished above with numerous pointed warts, which 

 are somewhat disposed in rows. Feet palmate, five-toed ; 

 claws 5-4. 



Plates of the margin, twenty-three ; of the sternum, eleven. 



Length three inches and a half, height one inch and a 

 half. 



a. Shell dark brown, very convex and sharp on the back, 

 with a conspicuous keel ; plates marked with radiating lines of 

 dusky, and with concentric striae. 



/3. Shell flattened along the middle of the back, so as to re- 

 semble the T. pensylvanica. 



