144 



The length of the carapace of fully grown adults may be a foot, some- 

 times probably more. The females have tails that scarcely project be- 

 yond the edge of the carapace, while that of the male is much longer. 

 Both Agassiz and Baur have noted the fact that the males are much 

 smaller than the females. Baur has also made the observation that the 

 males are not so numerous as the females {22, 22, 1122). It is not at all 

 improbable that such is the case ; yet it may be only apparently so, due 

 to fewer of the males being captured, on account of their smaller size, or 

 on account of the saving only of the larger, finer s-pecimens. 



The species inhabits North America from the St. Lawrence River to 

 Florida and west to the plains. I have note of its occurrence in the 

 rivers of Indiana at five })oints: Delphi (Agassiz); Madison (Yarrow) ; 

 Mt. Carmel, 111. (R. Ridgway) ; and Terre Haute (Blatchley). LeSueur 

 described the species from specimens taken at New Harmony. 



Habits. — This species, like all the soft shelled turtles, is wholly 

 aquatic, since they leave the water only on rare occasions. They delight 

 to remain about the roots of trees which have fallen into the water or in 

 drifts of timber. Here they can watch for prey and not be observed by 

 any supposed enemy. Away from such means of concealment they are 

 accustomed to bury themselves completely in the sand, leaving only their 

 heads exposed. 8ince their heads do not differ much in color from the 

 sand it is difficult for one to recognize them, even when the eye is directed 

 to them. When air is required it is obtained by stretching out the neck 

 until the pointed snout reaches the surface. The bead is then again 

 withdrawn. Like T. sjnniferus, this species no doubt enjoys a true 

 aquatic respiration. They subsist probably on insects, fishes, water snails, 

 and similar small animals. Agassiz found the larvse of neuropterous in- 

 sects in their stomachs. Max. Von Wied (103, xxii, 53) says that 

 LeSueur found in their stomachs worms, snails, fruits, and even hard 

 nuts. If there are potatoes growing near the water the turtles find their 

 way to them and devour the stems, of which they are very fond. 



The eggs are spherical in form, about seven-eights of an inch in diam- 

 eter, and have a thick, but brittle, calcareous shell. They are deposited 

 in the sand on the shores of the rivers where the adults live. The young 

 are flatter and more nearly circular than the adults. This species, like, 

 the other species of Trionyx, is regarded as a great delicacy. 



Trionyx agassizii, (Baur). 



Agassiz' Soft- Shelled Turtle. 



Trionyx ferox, in part, Boulenger, 1889, 84, 259; Platypeltis ferox, 

 Agassiz, 1857, 4, i, 400, and ii, pi. vi, fig. 3 (young), pi. vii, fig. 22. 

 (egg) ; Platypeltis agassizii, Baur, 1888, 22, xxii, 1121. 



