FAMILY CHELONIDZ. Pe | 
GENUS KINOSTERNON. § Spiz. 
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. 
KinosTERNON PENSYLVANICUM. 
PLATE Il. FIG. 4.— (CABINET OF THE LYCEUM.) 
Testudo pensylvanica. Epwarps, Gleanings, pl. 287. Penn. Arct. Zool. Suppl. p. 80. 
La Tortue rougeatre. Daun. Vol. 2, p. 182, pl. 24, fig. 1, 2. 
Cistuda pensylvanica. Say, Ac. Se. Vol. 4, p. 206. Le Contre, Ann. Lye. Vol. 3, p. 120. 
Kinosternon id. BrEt1, Zoological Journal, Vol. 2, p. 304. 
Emys id. Harwan, Med. and Phys. Researches, p. 155. 
Kinosternon pensylvanicum. Housroox, N. Am. Herpet. Vol. 2, p. 23, pl. 3; and Vol. 1, p. 127, pl. 21 of 2d Ed. 
Cinosternon. Wacu. 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 papille ; 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 
