Species of North American Tortoises. 131 



Shell gibbous, flattened on the back, ecarinate, oval, very 

 slightly emarginate behind, dusky or brown of difterent de- 

 grees of intensity. Vertebral plates more or less imbricate 

 behind ; the first long, narrower than the rest, resembling a 

 triangle with its apex pointing backwards and truncate, a little 

 elevated along the middle ; second, third and fourth hexagonal, 

 the anterior angles rounded, the lateral acuminate, the fifth 

 triangularly-pentagonal ; lateral plates large, pentagonal, ex- 

 cept the first which is quadrangular ; marginal plates small, 

 forming a narrow border around the shell, which is separated 

 from the lateral plates by a deep groove as far as the tenth, the 

 tenth and eleventh wider than the rest, continuous with the 

 last lateral and vertebral plates, being only distinguished from 

 them by the sutures ; intermediate marginal plate square, the 

 rest oblong. Sternum emarginate behind, jointed at the pec- 

 toral plates, and sometimes also imperfectly at the posterior 

 face of the abdominal, yellow (of which colour likewise is the 

 under side of the marginal plates), each plate with a dark 

 brown border where it joins the next ; scapular plate single, 

 triangular ; abdominal plates foursided, the rest triangular ; 

 supplementary plates of the wings triangular, interposed be- 

 tween the wings and the marginal plates, the posterior one very 

 large. Skin dusky cinereous, inclining to brown, head blunt, large, 

 and with the upper side of the neck, spotted with pale brown ; 

 jaws, sides of the neck, throat and chin more inclining to cine- 

 reous ; upper jaw with a hooked tooth ; chin with two warts. 

 Legs naked, fore legs with two folds or large scales on the 

 hinder side, and a few small scales beneath at the insertion of 

 the feet ; hind legs with eight or ten scales beneath. Irids 

 dark brown : tail naked, short, furnished at the tip with a 

 blunt nail. Feet palmate, five-toed ; claws 5-4. 



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



Length four inches, height one inch and three quarters. 



Inhabits from New-Jersey to Florida in ditches and muddy 

 streams: has a strong and not disagreeable odour of musk. 

 Preys upon small fish and other aquatic animals, bites readily 



