288 ZOOLOGY. 



animal. The principal food of the land tortoise consists of vegetable matter 

 as fungi, of slugs, &.c. Other species are found in the Old World, as C. 

 europa.a {pi. SI, Jig". 41, and pi. 90, Jig. 12). Sternothanriis, with some resem- 

 blance to the last genus, has the anterior half only of the lower shell movable. 

 The single North American species, S. odoratus, or the stinkpot of the 

 Middle States, is a small species, exclusively aquatic, and often caught on a 

 hook. It exhales a very disagreeable musky smell. Commonly confounded 

 with this species is Kinosternon pennsylvanicwn, a turtle of about the 

 same size, but with the lower shell in three pieces, of Avhicli the middle 

 is fixed, and the anterior and posterior move on this by cartilaginous 

 hinges. The next noteworthy genus is Chelonura, or the snapping-turtle 

 of the United States. Of this, there are two species, one confined to the 

 South-West, and of immense size. The genus Emys includes species 

 with depressed bodies and immovable plastron ; five toes to the feet, the 

 posterior with four claws only. Of this single genus there arc 17 species 

 known in the United States. The most remarkable is E. terrapin, the 

 common diamond-back terrapin, so highly prized by epicures. It is caught 

 in the brackish waters of the Chesapeake, and other bays and rivers, and 

 commands a high price. Another species, E. picta [pi. 81, Jig. 42), is ex- 

 ceedingly abundant. 



In the second sub-family of the Emydida, or the Pleiirodehs, the neck 

 and head are not capable of complete retraction within the anterior part of 

 the shell, but only partially to one side. The cranium is more or less 

 depressed, and the eyes are more or less superior, and approximated. The 

 skin Avhich covers the neck is closely adherent to the subjacent muscles, and 

 follows the neck in all its movements. None of the species belong to North 

 America : many, however, to South America. The most remarkable is 

 the Chelys tnatamata, or matamata tortoise of Cayenne, remarkable for the 

 numerous fringes and other appendages which give it so grotesque an ap- 

 pearance. 



Fam. 3. Trionycida. This family is known by the complete absence 

 of scales upon the body, the shell being covered by a soft skin, and with 

 free and flexible borders detached from the sternum. The feet and head 

 are equally clothed with a naked skin, the latter without visible tympanum, 

 and with nostrils prolonged into a kind of tube. Tlie feet are provided 

 with five toes each, wdth, however, but three claws. The species are all 

 highly aquatic, Avith a much depressed shell, which, with their oar-shaped 

 feet, well fits them for rapid progression in the water. But two genera are 

 known, Tryonix and Cryptopus ; species of Avhich are found in North 

 America, Asia, and Africa. Two species of Trionyx are found in the 

 United States, where they are known as the soft-shelled turtle. One 

 species is exceedingly abundant in the Mississippi and its tributaries. It 

 bites readily at a night line, and is esteemed, in many places, a great 

 delicacy. 



Fani. 4, or the Chelonidce proper, includes the marine species, which are 

 all of immense size. Their carapace is much depressed, and the upper jaw 

 usually presents^ a curved beak somewhat like that of a hawk. The feet 

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