ZOOLOG Y-REPTILES. 
3 
Char. 2. The head is depressed, covered with horny scutellae ; marginal scutes 23-27, those 
of the sternum 11-12. 
Char. 3. The skull is generally depressed and solid, with a distinct bony margin, and covered 
with horny plates ; the dorsal plates 13 with twelve pairs of marginal plates, the caudal pair 
being separated by a distinct suture; nuchal plate narrow. The sterno-costal commissure is 
generally long, and usually furnished with a distinct and rather large axillary and inguinal 
plate. The sternum has 11 or 12 shields, the gular pair being sometimes united, hut never 
having an extra plate between them as in Chelydae. 
Char. 4. Live in ponds and ditches ; only take their food when in water ; eggs oval and 
white; motions rapid ; living on mollusca, worms, insects, and carrion ; inhabit warm and 
temperate climates.—(Gray.) 
EMYS, Brogniart 
EMYS (NIGRA, Nob. 
Sp. Char. —Shell oblong-ovate, slightly compressed at the sides, and emarginate, but not 
distinctly serrated posteriorly; latero-posterior margins of carapax everted; nuchal plate 
narrow, truncate anteriorly, broader posteriorly; 24 marginal plates, the two posterior more or 
less quadrilateral, the two adjoining pentagonal; color blackish above, the upper part of head 
and neck presenting numerous very small yellow spots upon a black ground; anterior extremi¬ 
ties with a tinge of yellow ; under jaw and throat yellow, with dark colored markings ; plastron 
yellow in the middle, with large blotches of black or dark brown at the sides, and anteriorly 
and posteriorly ; under surface of tail and extremities blackish ; tail of moderate length. 
Dimensions. —Length of head, 1 inch ; breadth, $; length of carapax, inches, measured 
along curvature superiorly ; breadth at middle, 5| inches ; of tail, 2§. 
Habitat. —Posa creek, southern part of Upper California, where it is very abundant. 
Gen. Obs. —This species resembles none of the North American Emydes with which I am 
acquainted. Its dark color puts one in mind of, but is not so jet a black as that of Sternothaerus 
niger of Madagascar. 
