164 CHELONIANS. 



The Pleuroderes have the neck retractile on one side of the 

 carapace, without their having the power of drawing it between 

 their fore feet, and under the buckler and plastron, like the 

 Cryptoderes. Chelys matamata (Fig. 38) belongs to this division. 

 This species lives in stagnant water, and is altogether remark- 

 able for its singular appearance for its depressed, wide, and tri- 

 angular nostrils, prolonged into a proboscis ; its wide gape, 

 rounded jaws, and the cutaneous appendages to the chin. This 

 is sometimes called the Bearded Tortoise. 



POTAMIANS, OR RlVER TORTOISES. 



The River Tortoises live constantly in the water, only coming 

 to land occasionally ; they swim with much ease below and 

 on the surface. The carapace is very broad and flat ; the toes 

 united up to the claws by broad flexible membranes. These 

 membranes change the feet into true paddles, which perform 

 the office of oars. They seem to attain a considerable size, 

 one kept by Pennant for three months weighing twenty pounds, 

 its buckler not reckoned ; the neck measuring twenty inches 

 in length. The upper parts of their bodies vary in tint from 

 brown to grey, with irregularly marbled, dotted, or ocellated 

 spots ; the underpart is a pale white, rosy, or purple tint. Sinuous 

 brown, black, or yellow lines are symmetrically disposed on the 

 right and left, principally on the neck and on the limbs. 



During the night, when they think themselves safe, the River 

 Tortoises seek repose on the rocks and islets, or on timber floating in 

 the rivers, from which they plunge into the water on the slightest 

 noise. These Tortoises, which accommodate themselves so perfectly 

 to the medium that they inhabit, are continually at war with 

 the fishes, reptiles, mollusks, and other denizens of the rivers. 

 They are voracious and active, and are relentless enemies to the 

 young of fishes, and especially of Crocodiles. 



The carapace of the River Tortoise, Trionyx, is soft, covered with 

 a flexible cartilaginous skin resting on a greatly-depressed osseous 

 disk; its upper surface is covered with shrivelled sinuosities. As 

 they are destitute of scales these Tortoises are said to be soft; 

 their flesh is much esteemed, and they are angled for with hook 

 and line, baited with small fishes or living worms and mollusks, or 



