OCR Text |
Show 1873.] ALVEOLAR SURFACES OF TORTOISES. 727 PYXIS ARACHNOIDES, Gray, Cat., App. p. 14. (Plate LX. fig. 7, alveolar processes of jaws.) Section IV. Alveolar surface of the upper jaw narrow, slightly concave on the sides of the lower jaw, very narrow, linear, with a slightly raised edge on each side, and a very slight longitudinal ridge across the front. The lower jaw slender and weak. Hinder part of the dorsal disk separated from the front and central part by an irregular transverse cartilaginous suture. Sternum undivided. Tribe VII. KINIXYINA. 1. K I N I X Y S. Skull rather elongate. Forehead flat. Orbits oblong, longitudinal. Nose-hole square, with a prominence in the centre of the upper and lower margins. Intermaxillary rather high. Front edge of upper jaw even. Alveolar surface of upper jaw narrow, rather wider behind, with a very slight indication of a thickening on the hinder part of the inner edge; centre slightly concave in front, and becoming much more concave as it proceeds between the inner nostrils. The groove behind the inner nostrils rather wider in the middle behind. Lower jaw weak, slender, rounded in front; the alveolar surface narrow, linear the whole of its length, and with very narrow acute edges. K I N I X Y S EROSA, Gray, Cat., App. p. 16. (Plate L X . fig. 8, alveolar processes of jaws.) This order of Tortoises may be thus arranged :- I. The dorsal disk solid. f The sternum solid. A. The alveolar surface of the upper and lower jaw with two ridges, one on each side extending nearly the whole length. a. The centre of the alveolar surface of the upper jaw with a longitudinal ridge. Xerobates. b. The centre of the upper alveolar margin concave, subcircular. The hinder ridge of the alveolar process of the lower jaw nearly united in front. Elephantopus, Megalochelys, and Asterochelys. The hinder ridge of the lower jaw separated by a broad space in front. Anal margin of plates separate. Pectoral plates reaching the centre of the sternum. Chelonoides. Anal margin of plates united together. Pectoral plates broad, reaching the centre of the sternum. Scapia. Pectoral plates narrow, not reaching the centre of the sternum. Manouria. |