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Show 1869.J DR. J. E. GRAY ON THE TORTOISES. 183 looks as if it had lived in dirty water. They both have the front lobe of the sternum about one-fourth of its length longer than the abdominal shields, which are short. c. The sterno-costal suture and the abdominal shields not so long as the front lobe of the sternum; the hinder lobe of the sternum slightly truncated behind. Thorax not keeled. Vertebral plates as broad as long. 3. SWANKA FASCIATA. Head olive, with a dark-edged pale streak from the nostril, over the eye, to the upper part of the tympanum (it is narrow before, and wider behind the eyes), and with a streak from the lower edge of the orbit, over the angle of the jaw on the side of the neck; occiput and back of neck white-spotted. The lobes of the sternum are rather narrower than the opening of the thorax. Hab. ? (from M. Brandt). KlNOSTERNON. 1. KlNOSTERNON PENNSYLVANICUM. The skull in the British Museum is depressed, ovate triangular, crown rhombic, narrow behind, short, only slightly produced behind the orbits ; orbit lateral, large ; zygomatic arch broad, rather convex and prominent behind, including the whole front edge of the small tympanic cavity ; palate deeply concave in the centre, with three longitudinal ridges on each side of the central line, very narrow behind; upper jaw with a broad intermediate ledge edged with a slightly raised ridge; lower jaw with a shelving edge to the back, and hooked in front. 2. KINOSTERNON HIRTIPES, Wagler, N. Syst. Amph. The skull is figured by Wagler in N. Syst. Amph. t. 5. f. xxxi.- xxxviii. The figure is very like the skull of Chelydra. Fam. III. EMYDIDAE or TRUE TERRAPINS. When my two papers on the skulls of Chelydradse and Trionychidse were published, I hoped that some of the American zoologists, who have so many species of one group (Emydidee) living in their country, and consequently at their command, would take up the subject. But they have not done so ; and as the British Museum has received a few more specimens, 1 have determined to do the best I can with the specimens at m y command, and the figures of the specimens that have been published by Wagler and others. It is to be regretted that Agassiz, in his notes on the American Terrapins in his * Contributions,' has confined his attention so completely to the external characters, and the development of the young animal. He does make some observations on the form of the jaws ; but they are so indistinct and general that they afford very little information. |