224 DR. J. E. GRAY ON THE TORTOISES. [ Mar. 11, 
** The alveolar surface of the upper jaw with two arched ridges, 
the inner one near the inner margin, the outer near the outer 
margin, and interrupted by a deep pit in front. Lower one 
strongly toothed on the edge, with a subcentral ridge, with a 
large conical prominence in the middle, and a deep pit on each 
side in front of it. Algivorous. 
2. CHELONIA. 
3. Mypas. 
Cheloniat+, Gray, Cat. Shield Rept. p. 75. 
Fam. Il. SpHarcipipz&. 
Sphargidide, Gray, Ann. Phil. 1825, x. p. 212. 
The thorax covered with a continuous soft skin. Nose blunt and 
broad ; nostrils on the upper surface of the nose. Upper jaw with 
a deep notch on each side. Eyes very large. 
Skull oblong; crown swollen, subglobose behind. Orbits very 
large. Nose-cavity superior, carried up by the elongated erect 
intermaxillary bone. Maxillary bone with a deep notch in the front 
of the lower edge, near the intermaxillary. Lower jaw produced, 
acute, bent up in front. 
Dermatochelyde, Fitzinger ; Wagler, Amph. p. 20, t. 1. f. 1. 
Sphargiide, Agassiz, Contrib. 
Spwarcis, Merrem=Coriudo, Fleming; Sytina, Wagler; Der- 
matochelys, Fitzinger. 
Sphargis mercurialis. 
Mr. E. Gerrard has prepared a beautiful skeleton of a very young 
specimen of this genus, about 4 inches long. It is a most curious 
preparation, with its odd-shaped head with very large nasal cavities 
and orbits, extremely large fore fins with extremely slender fingers, 
