FAMILY CHELONIDjE. 21 



GENUS KINOSTERNON. Spix. 



Head sub-quadrangular, pyramidal, covered with a single plate. Jaws slightly hooked. 

 Warts at the chin. Marginal plates twenty-three. Sternum subdivided into three sec- 

 tions ; the anterior and posterior movable, the central fixed. Plates of the sternum eleven. 

 Supplemental plates very large. Tail moderate or long. 



THE MUD TORTOISE. 



KlNOSTERNON PENSYLVANICDM. 



PLATE II. FIG. 4. — (CABINET OF THE LYCEUM.) 



Testudo pensylvanica. Edwards, Gleanings, pi. 287. Penn. Arct. Zool. Suppl. p. 80. 



La Tortue rougeitre. Dacd. Vol. 2, p. 182, pi. 24, fig. 1, 2. 



Cistuda pensylvanica. Say, Ac. Sc. Vol. 4, p. 206. Le Conte, Ann. Lye. Vol. 3, p. 120. 



Kinosternon id. Bell, Zoological Journal, Vol. 2, p. 304. 



Emys id. Harlan, Med. and Phys. Researches, p. 155. 



Kinosternon pensylvanicum. Holbrook, N. Am. Herpet. Vol. 2, p. 23, pi. 3; and Vol. 1, p. 127, pi. 21 of 2d Ed. 



Cinosternon. Wagl. Bonap. Chel. Tab. analytica, p. 7. 



Characteristics. Dusky brown. Shell vaulted. Upper and lower jaw hooked. The penul- 

 timate marginal plate on each side, dilated. Tail with a horny point. 

 Length four inches. 



Description. Shell oval, smooth, elevated behind, flattened above, descending rapidly behind, 

 where it is minutely emarginate ; the surface is covered with numerous obsolete angularly 

 concentric furrows. First vertebral plate triangular, with a truncate apex behind ; the second, 

 third and fourth, hexagonal ; the third smallest : all sub-imbricate behind. Lateral plates 

 large, imbricate. Marginal plates elevated above the plane of the lateral plates, and sepa- 

 rated from them by a deep furrow as far as the tenth pair, which, together with the eleventh, 

 is continuous with the plane of the lateral and vertebral plates, and much higher than the 

 others ; the intermediate plate small, linear, dilated beneath. The sternum of eleven plates, 

 somewhat concave, notched behind, with a joint at the pectoral plates, and another joint more 

 or less obvious at the posterior margin of the abdominal plates. Gular plates united into one, 

 triangular. Brachial plates obliquely four-sided ; the thoracic triangular, smaller : both pair 

 united to each other, and attached by a ligamentous hinge to the fixed abdominal pair, which 

 is largest. This last pair connects to the marginal plates by two accessory plates, of which 

 the posterior is largest, subtriangular. The posterior angle of the femoral plates forms a 

 notch with the border of the caudal plates, which are emarginate. All the plates of the 

 sternum with deeply sculptured angular and parallel lines. Head large. Upper and lower 

 jaw with a hooked tooth. Skin of the neck with four series of cutaneous papillae ; two others 

 larger, approximated beneath the chin. Fore feet naked, with two large scaly folds on the 

 upper side, and small scales beneath, with five robust but short claws. A few scattering 



