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Show 178 DR. J. E. GRAY ON THE TORTOISES. [Mar. 1 1, zygomatic arch complete, broad in front, narrowed behind and attached to the upper front part of the tympanic cavity ; mastoid bone acute behind, keeled on the outer upper side, hollow; palate flat; internal nostrils anterior, with a short, oblong, slightly sunken concavity behind, each separated from the other by a blunt ridge; alveolar plate very narrow, linear, with a slight ridge on the inner margin; upper beak with a smooth edge and an entire, recurved, sharp tip. Lower jaw moderately strong, rounded below in front; lower beak with a simple sharp edge, rather produced and acute in front, with a slightly concave linear inner margin. 5. PYXICLEMMYS, Gray, P. Z. S. 1863. 6. LUTREMYS, Gray, P.Z.S. 1855 & 1863. The anatomy of the animal is well described by Bojanus. The skull is figured by Cuvier (Oss. Foss. v. t. 11. f. 13-16) and Wagler (in N. Syst. Amph. t. 5. f. xv.-xviii.). There is a skeleton in the British Museum ; it has a well-developed zygomatic arch. 7. NOTOCHELYS, Gray, P.Z. S. 1863. ** Lobes of the sternum moveable in the young state, often becoming anchylosed. 8. CYCLEMYS, Gray, P.Z. S. 1855, p. 198, 1863, p. 177. The thorax convex or depressed. The sternum flat or slightly convex, with the lateral symphyses well marked, truncated before and notched behind; the cross suture indistinctly marked and narrow, more or less obliterated in the adult, covered with the produced front edge of the ventral shields. The legs covered with large, bandlike thin plates in front. The toes banded above, the front one short, webbed. The hind feet flattened, with the toes broadly webbed ; the hinder edge keeled and angularly produced. CYCLEMYS ORBICULATA. Skeleton in the British Museum, from Java. Skull elongate ; zygomatic arch rather narrow, distinct. The alveolar surface of the upper jaw is narrow, with a well-marked longitudinal groove the whole length of the outer edge, and with a raised internal margin. Edge of the upper jaw rather arched on the side, with a small central tooth. The lower jaw with a simple, short edge shelving inwards in the centre, and with a rather concave surface on the inner side, and a sharp, produced central anterior process. Fam. II. CHELYDRADAE. Head large, covered with a thin, hard skin, or hard bony plates ; temporal muscle large, covered with the skin, and protected on the edge by a well-developed band-like, zygomatic arch. Eyes lateral or |