155 



keels, a mediau and two lateral ; these almost wholly disappearing in 

 the adults ; ofteu a depression along the middle of the back. First and 

 second vertebral scutes considerably longer than broad. Plastron well 

 developed, lacking but little of filling up the opening of the carapace. 

 The anterior lobe rounded, extending even beyond the end of the cara- 

 pace, freely movable on the transverse hinge. Gular plate single, 

 small and triangular. The humerals large, and the suture between 

 them much longer than that between the pectorals. Hinder lobe of 

 plastron movable on the fixed portion ; notched behind. Head of mod- 

 erate size ; snout not greatly projecting ; lower jaw hooked. Soft skin 

 with a few or no fleshy papillse ; a pair of barbels behind the symphysis 

 of the mandibles. Males with two patches of sharp-edged scales, one 

 above the hollow of the knee, the other below. Tail of the males pro- 

 jecting beyond the shell, ending in a horny curved nail. 



Color of the carapace horn-color or brown, with the sutures black. 

 Plastron yellow or brown, with the lines of growth usually very distinct. 

 Soft skin above brownish, with spots of yellow. A yellow stripe from 

 the snout over the eye and back on the neck. Another from the eye to 

 the coruer of the mouth and to the angle of the jaw. Skin of the lower 

 surfaces yellow. Size small, becoming probably not more than 5 inches 

 from front to back of carapace. 



Distributed from Canada to Florida and west to Texas and Western 

 Kansas. In Indiana it has been taken by Mr. Robert Ridgeway, at 

 Wheatland, in Knox county. Prof. W. S. Blatchley reports to me 

 that he has collected a specimen at Terre Haute. Mr. Ridgway states 

 that it is common on the bordei's of Monteur's Pond, in Knox county. 



Habits. — This tortoise is quite similar to the musk turtle in its mode 

 of life. It remains about ponds and muddy ditches, where it can bury 

 itself in the mud whenever it becomes alarmed. They are more in- 

 clined to passively withdrawing into their shells when attacked than is 

 the musk turtle, since the shell forms a more perfect protection and 

 their jaw^s are not fitted for the infliction of severe wounds. Their food 

 consists of fish, insects and similar small animals. They are said to 

 take the hook readily, but they nibble the angler's bait so slyly that 

 their presence is not observed for some time. Their eggs are similar to 

 those of A. odorata, but rather larger. They are laid in similar situa- 

 tions. 



Family X. TESTUDINIDiE. 



Shell completely ossified, varying in form from broad to narrow and 

 from high to depressed. Greatest height about the middle, whence the 

 shell elopes in all directions, flaring at the borders. Carapace with the 

 typical number of scutes, 4, 5, 4, with 25 marginals. Plastron large,, 

 composed of 9 bones, the entoplastron being present. Plastral scutes- 

 11 or 12 ; the pectorals coming into contact with the marginals. 



