| OCR Text |
Show 1869.] DR. J. E. GRAY ON THE TORTOISES. 221 sternal callosities are scarcely developed, only showing a slight roughness on the surface. Head olive, with a black central streak from the snout to between the eyes, which divides behind into three diverging streaks on the crown and nape ; a streak from the nose, through the eye, and continued on the temple, to the side of the neck. The alveolar surface of the upper and lower jaws very broad the whole length of the outer edges ; the alveolar surface of the upper jaw is so large as to cover the greater part of the palate, much more so than in Trionyx gangeticus; in the lower jaw it is very broad, as broad behind as before, and slightly concave. The central palatine groove in front of the internal nostrils narrow, deep. The bones of the dorsal shield are distinctly marked and separate; the vertebral plates are very narrow, nearly twice as long as broad ; the costal ones are linear, scarcely broader at the outer ends, the last one being the least and narrow at the outer end. The odd bone in front is quite separate from the granular buckler, covered with skin, and quite smooth. The lateral sternal callosities are scarcely developed, only showing a slight roughness on the surface. The hinder pair of sternal bones are broad at the inner end and united together in front of the inner edges by two broad lobes. Very like the figure in Cuvier's ' Ossemens Fossiles,' v. t. 23. f. 5. 6. ASPILUS. The odd bone in front of the dorsal shield in the younger specimen is separate, and smooth on the upper surface, and it becomes pitted and united to the costal by a straight suture in the adult animal. 8. POTAMOCHELYS. The odd anterior bone of the dorsal disk in the young animal is pitted on the surface and separate, but in the older ones it is united to the dorsal disk by a straight suture. The skull resembles that of Cyclanosteus. 12. CALLINIA. Head small, elongate ; face narrow, tapering; eyes lateral, superior. The jaws weak ; the alveolar plates narrow at the hinder part, triangular and broader in front. The lower jaw slender, narrower at the hinder part of the sides. The central palatal groove in front of the internal nostrils rather wide and deep. The dorsal disk oblong, broad. The odd bone in front of the dorsal shield separate, transverse, and pitted in the young animal; in the older one it is united to the front costal bones by a straight edge with two round perforations, one on each side of the central part. The vertebral callosities narrow. The costal callosities scarcely broader at the outer edge, except the fifth and sixth pairs; the hinder pair short, and narrow at the outer ends. Sternal callosities four ; the lateral pair broad on the inner side ; the hinder or anal pair oblong triangular, oblique, with a straight inner edge. Aspidonectes, sp., Agassiz, not Wagler. |
