CHELONIA. 11 



Chelys, Dum.(l) 



The Chelydes resemble fresh water Tortoises in their feet and 

 nailsj their envelope is much too small to contain their head and 

 feet, which are very large, and their nose is lengthened out into a 

 small snout; their most dominant character, however, consists in 

 their mouth, which opens crosswise, being unarmed with the horny 

 beak common to the other Chelonise, and similar to that of certain 

 Batrachians, the Pipa in particular. 



Test, fimbria, Gm.; La Matamata; Brug. Journ. d'Hist. Nat. 

 I, xiii; Schoepf. xxi. The shell studded with pyramidal eleva- 

 tions, and the body edged all round with a pinked fringe. It is 

 found in Guiana. 



Trionyx, Geoff. 



The Soft-shelled Tortoises have no scales, the shell and sternum 

 being simply enveloped by a soft skin; neither of those shells is 

 completely supported by bones, as the ribs do not extend to the 

 edge of the upper one, and are united with each other only for a 

 portion of their length, the parts analogous to the sternal ribs being 

 simple cartilage, and the sternal pieces partially notched as in the 

 sea-tortoises, not covering the whole lower surface. After death, 

 the very rough surface of the ribs may be perceived through the 

 dried skin. Their feet, like those of the fresh-water Tortoises, are 

 palmated without being lengthened, but only three of their toes are 

 possessed of nails. The horn of their beak is invested externally 

 with fleshy lips, and their nose is prolonged into a little snout. Their 

 tail is very short. They live in fresh water, and the flexible edges 

 of their shell aid them in swimming. 



Trionyx segyptiacus, GeofF. Ann. du Mus. XIV, 1; Test, tri- 

 unguis, Forsk and Gmel. (The Tyrse), is sometimes three feet 

 in length, and of a green colour spotted with white; its shell is 

 but slightly convex. It devours the young Crocodiles the mo- 

 ment they leave the egg, and is thus of more utility to Egypt 

 than the Ichneumon. (2) 



Test. ■ f er ox fGm.; Phil. Trans., LXI, x, 1 — 3; cop., Lacep. I, 

 vii; Schoepf. xix (The Soft-shelled Tortoise of America), in- 

 habits the rivers of Carolina, Georgia, the Floridas, and of 

 Guiana. It remains in ambush under roots of reeds, &c. whence 

 it seizes birds, reptiles. Sec, devours the young Alligators, 



(1) Merrem prefers calling this genus by the barbarous name of Matamata. 



(2) Sonnini, Voy. en Egypte, toni. II, p. 553. 



