546 FAMILY TRIONYCIDJE. 



rounded by soft lips, the nose usually elongated into a proboscis, 

 and the head and neck often furnished with lobes and append- 

 ages of very curious forms. In their habits these Tortoises agree 

 with those of the last family ; they frequent the ponds and rivers 

 of the warm parts of both hemispheres, feeding principally upon 

 Fish. A few species are even found in Australia, where they 

 are the only representatives of this order. 



485. The two other families of this order are almost exclu- 

 sively aquatic ; coming on shore only to deposit their eggs, and 

 doing this stealthily by . night. In the TRIONYCIDJE, or River 

 Tortoises, however, the structure of the feet does not depart so 

 widely from the forms of the preceding families as it does in the 

 Turtles ; for although the toes are connected by a web, and only 

 three of them are furnished with claws, they are still distinguish- 

 able. Like the Emydidae, these Tortoises are exclusively car- 

 nivorous ; and they eat their food in the water. They subsist 

 upon Fishes, Reptiles, Birds, &c., upon which they dart out from 

 their hiding-places, and snap at their prey with great energy 

 and rapidity, The edges of their mandibles are so sharp and 

 firm, that they can readily bite off a man's finger. From this 

 vigorous action of the jaws the best known species has received 

 the name of the Snapping Turtle. The ossification of the cara- 

 pace is very imperfect; the costal plates are only broad and 

 united towards the centre of the shell, and become narrower to- 

 wards the circumference, radiating like the spokes of a wheel ; 

 the plastron also is imperfectly ossified ; and instead of the hard 

 horny plates of the preceding families, the carapace is covered 

 with a tough leathery skin. Hence these animals are sometimes 

 called Soft Tortoises. No species of this family is European ; 

 but almost every large river and lake, in the warmer regions of 

 the Old and New World, is inhabited by them. They are par- 

 ticularly numerous in the Ganges ; where they prey, with the 

 Gavials, on the human bodies which are always floating in that 

 stream. The Snapping Turtle above referred to, is abundant 

 in the fresh waters of North America, where it devours great 

 quantities of young Alligators ; and another species inhabiting 

 the Nile, is said to be equally destructive to the Crocodile. The 



