TURTLES AND TORTOISES 59 



mens the writer has hunted for a derelict bough, four 

 to five inches in diameter, minus the bark and quite 

 slimy with a growth of microscopic algce. This should 

 be so fastened that about one-third of its diameter pro- 

 trudes from the water. Treated thus, the writer has 

 never examined any of his specimens that had a sore 

 plastron. The bottom of the tank should be covered 

 with two to three inches of fine sand, for the turtles 

 delight in burrowing. 



Among the Old World species of Trionyx, a charac- 

 ter is to be at once noted in relation to the carapace — a 

 character not apparent on the American species, except 

 with extremely old individuals, or specimens that have 

 become emaciated. This is the practical exposure, over 

 the greater portion of the back (the central portion) 

 of the sheet of bones to which are fused the ribs and 

 vertebrae; around this is a soft, leathery margin which 

 sinks downward as the animal emerges from the water. 

 On the bonv, dorsal sheet the sutures of the bones are 

 sharply delineated; the entire surface is coarsely punc- 

 tulated — like old bone that has disintegrated to some 

 extent. The characteristic is not so evident on young 

 individuals. 



The Ganges Soft- Shelled Turtle, T. gangeticus, 

 is one of the largest of the Asiatic species. Dull olive 

 and finely-spotted with black, the shell of an adult may 

 be two feet long. T. hurum, another Indian species, 

 has a dull olive shell when adult, while the young have 

 a startling coloration, being greenish with several pairs 

 of round, eye-like spots on the back — each with a black 

 center, then a yellow border and outside of this suc- 

 cessive rings of olive and black. 



One species, T. triunguis — the only African member 

 of the genus — has an enormous range, extending from 



