44 TRIONYCHIDyE. 



Test. Matamata, Brug. Jour. Hist. Nat. Par., t. 12. cop. 

 Test fimhriata, Schoepf, t. 21; Shaw, Zool. iii. t. 8, and 

 Daud. t. 20, f. 1. Malamatajimbriata, Merrem. — Cuv. Os. 

 Fos. V. 189, t. 11, f. 21, 24; t. 12, f. 3, f. 8, f. 12, f. 13, 

 f. 20, f. 37, f. 41. 



Chelys fimhriata, Schw. Spix. t. 11. Guerin. Icon. 

 Rept. t. i. f. 5. Test. Rapara, Freminv. 



3. Scutellis costalibus planis, gula unicolore. v. GeofiF. 

 Ann. Mus. xiv. 19, (PuUus.) 



Hab. in America Meridionali, Surinam. Guiana, et 

 Brasilia. Mus. Col. Surg. (Skeleton.) 



The branches of the sternum are separate in front. 



Fam. //^.— TRIONYCHID^. 



Pedes palmati, unguibus 3-3 elongatis acutis ; caput 

 depressum, naribus elongatis tubulosis. Testa sternumque 

 rugosa cute cartilaginea tecta, margine explanata flexibili ; 

 sternum annul iforme symphysi cartilaginea testae adnexum. 



The head is flattened, oval ; the jaws horny, edged with a 

 membrane; the neck long and contractile; chin not bearded; 

 the body oval, depressed ; the upper part of the ribs united ; 

 the ends free and produced, usually only united to the 

 sternum by means of the cartilaginous coat with which they 

 are covered, but sometimes furnished with a few bones in 

 the front and hinder margin of the symphysis. 



The sternum is formed of a ring of bones ; the two lateral 

 pairs of bones being connected together in front, by means 

 of the angularly bent central bone, which has one of the 

 similarly-shaped first pair of bones placed on each of its 

 outer edges. It has a cartilaginous centre, the bones often 

 furnished with callosities in the prominent parts. The shell 

 and sternum both covered with a cartilaginous skin, which, 

 when dry, exhibits the dotted structure of the bones through 

 its surface, and is expanded on its edge into a flexible 

 margin. The feet have short webbed toes, b-b ; the two 

 outer on each foot clawless ; claws 3-3, sharp, long, and 

 incurved; the tail short. 



These animals live in the large rivers and lakes of warm 

 regions, eating mollusca, small animals, and carrion ; they 

 use the flexible margin of their shells in swimming ; their 

 eggs are spherical. 



