1870.] DR. J. E. GRAY ON THE GENUS BARTLETTIA. 719 
In my paper on the genus Podoenemis in the ‘ Proceedings’ of 
the Society | pointed out that the Podocnemis expansa of Wagler 
and the Emys ewpansa of Cuvier, which had been considered the 
same species, had very different skulls, and I entered into the details 
of the differences between them. 
In my paper in the ‘ Proceedings’ of the Society for 1864, p. 133, 
I formed them into separate genera. 
Iu Bartlettia and Podocnemis expansa both the ischiadic and 
iliac bones are affixed by a bony suture to the sternum. 
The thorax of the animals of this family has the cavity con- 
tracted, like the shells of the greater part of the Bataguride of 
India. Ina very large specimen of Podocnemis expansa the front 
contraction is separated from the margin of the cavity by a con- 
siderable space, and may be so in younger specimens; in the genus 
Bartlettia it is continuous with the margin of the cavity, as in all 
the Batagurs I have examined. 
* 
Tribe I. PELTOCEPHALINA. 
The head high, subcompressed ; parietal bone entirely covering 
the temporal muscle. Nose produced, rounded above, without any 
longitudinal groove. 
1. PELTOCEPHALUS. 
P. rracaxa, Gray, Supp. Cat. Sh. Rept. p. 84. B.M. 
Tribe II. PopocnemMINa. 
Head depressed ; parietal expanded, covering the upper part of 
the temporal muscle, leaving a broad rounded notch in the skull, 
between the end of the maxilla and the tympanic bone. Nose flat- 
tened, with a deep longitudinal groove. 
2. CHELONEMYS. 
Head elongate ovate; the alveolar surface of the upper jaw rather 
sinuous, convex in front and shelving behind, with two diverging 
ridges, separated by a broad longitudinal depression, the inner one 
low and indistinct. Lower jaw with a sharp outer edge and a deep 
longitudinal concavity, the inner margin elevated, divided by a cen- 
tral longitudinal groove into two ridges; the central notch pro- 
duced forward between the under margin towards the apex of the 
central beak. (Cuvier, Oss. Foss. v. part 2, pl. 11. figs. 11, 12.) 
C. puMERILIANA, Gray, Suppl. Cat. Sh. Rept. p. 83. B.M. 
3. PopoCcNEMIS. 
Head short and broad; alveolar surface of upper jaw flat, with 
three diverging ridges, separated by a flat rugose space in the middle, 
the inner one low and distinct ; lower jaw with a sharp outer edge, 
a deep longitudinal concavity, the inner margin elevated, divided 
