14 CHELONIA. 
Cinosternum shawianum, Bocourt, Journ. Zool. 1876, p. 397 (not of Bell, which is the true C. 
scorpioides from Guiana) ; Sumichrast, Bull. Soc. Zool. France, 1880, p. 169. 
Hab. Mzxico (coll. Brit. Mus.), Tonala in Chiapas (Swmichrast). 
Shell with three keels, placed close together and disappearing in very old examples ; 
first vertebral scute as broad as, or even broader than, long. Sternum not emarginate 
behind ; the central portion shorter than either of the two lobes; joint of the hind 
lobe well developed and straight; gular plate as long as the median suture of the front 
lobe ; axillary and inguinal scutes not in contact with each other. 
The tail is very thick in the male and armed with a curved claw; short, tubercular, 
and provided with a much smaller claw in the female. The head is greyish, mottled 
with yellow, especially on the cheek ; jaws yellow, with black markings, of which the 
most constant occupies the median line of the lower jaw; middle of the throat mottled 
with grey. 
The principal characters of this species are already indicated in a very young speci- 
men only a few days old; its sternum is yellow with black subsymmetrical markings 
arranged chiefly along the median line. 
Besides some specimens of the origin of which nothing is known except that they 
came from Mexico, I have examined four examples collected by Sumichrast at Tonala 
(Chiapas); the largest of them are 5 inches long, a size which this species does not 
seem to exceed. As far as is known at present, it does not seem to occur beyond 
Mexico. 
The old female figured has only four claws on the fore foot. 
8. Cinosternum triliratum. 
Kinosternum triliratum, Leconte, Proc. Ac. N. Se. Phil. 1859, p. 6. 
Hab. Mexico (Pease). 
Shell with three strong keels ; sternum bivalved, entire and rather pointed behind; 
jaws yellow, varied with black (the upper entire, not hooked*). Gular large, tri- 
angular ; inguinal scutes long, rather wide, joining the axillaries. 
I have not seen specimens of this species. 
4. Cinosternum albogulare. 
Cinosternon albogulare, Bocourt, Miss. Sc. Mex., Rept. p. 24; Journ. Zool. 1876, p. 399. 
Hab. Costa Rica (Bocourt). 
Shell with three keels, sternum not emarginate behind. The first vertebral scute 
longer than broad ; gular shorter than the median suture of the front lobe ; fixed por- 
* The hook on the upper jaw is not a specific character ; it is developed with age, at least in those species 
of which I have been able to examine individuals of different ages. 
