OCR Text |
Show 1870.] DR. J. E. GRAY ON THE GENUS BARTLETTIA. 719 In my paper on the genus Podocnemis in the ' Proceedings' of the Society I pointed out that the Podocnemis expansa of Wagler and the Emys expansa 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 m y paper in the ' Proceedings' of the Society for 1864, p. 133, I formed them into separate genera. In 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 contracted, like the shells of the greater part of the Bataguridae of India. In a very large specimen of Podocnemis expansa the front contraction is separated from the margin of the cavity by a considerable 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 auy longitudinal groove. 1. PELTOCEPHALUS. P. TRACAXA, Gray, Supp. Cat. Sh. Rept. p. 84. B.M. Tribe II. PODOCNEMINA. 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 flattened, 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 central longitudinal groove into two ridges; the central notch produced forward between the under margin towards the apex of the central beak. (Cuvier, Oss. Foss. v. part 2, pl. 11. figs. 11, 12.) C. DUMERILIANA, Gray, Suppl. Cat. Sh. Rept. p. 83. B.M. 3. PODOCNEMIS. 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 |