MUSEUM OF COMPARATIVE ZOOLOGY. 125 



curved prominence at the symphysis. Carapace broad, arch comparatively 

 low, with three low ridges, slightly concave near the margin. Paddles broad, 

 rounded on the margins. 



Adult. — Body broad, depressed, subelliptical, broadest near or behind the 

 middle, concave near the lateral margins, flattened over the second to the 

 fourth vertebral plates ; head larger and broader than that of C. mydas or 

 C. virgata, broad posteriorly, convex on the occiput, flattened between and 

 compressed in front of the eyes. Upper jaw not serrated, outline nearly 

 straight, with the notch at the symphysis almost obliterated, vertically grooved 

 on the inner face. Lower jaw serrated, bearing a curved fang-like prominence 

 on the symphysis. Carapace broad and spreading posteriorly, arch very low. 

 Paddles comparatively small, anterior narrow and pointed, posterior short, 

 truncate, indented between the digits. One pair of elongate frontals. Ver- 

 tical small, short, broad, pentagonal, acute-angled in front. Supraocular large, 

 broad. Interparietal broader than long, surrounded by seven plates, vertical, 

 supraoculars, parietals, and occipitals. Postorbitals four (3-4), lower large. 

 Plates of carapace not imbricate, smooth in young and adult, costal series four 

 each, five vertebrals, and twenty-five marginals. Sternal plates thirteen, in 

 two series of six each, preceded by a small triangular plate at the neck. Lateral 

 plates of plastron four on each side, preceded by a pair of small, and these 

 again by several smaller brachials. The specimens described are from the 

 East Indies and North Australia. Applying the line to the shell the Aus- 

 tralian specimen measures in length 36-| inches, and in width 30 inches ; its 

 height is 9 inches. A specimen of G. mydas has a length of 39| inches, a width 

 of 34^ inches, and a height of 1 1 inches. 



C. depressa differs much from the species described by Dumeril and Bibron 

 as C. virgata. It is less truncated and more deeply indented in front than 

 either of the other species of the genus. A transverse section across the 

 middle of the body is not what would be called roof-shaped, but more of the 

 shape of a bow of considerable curvature, a portion of the middle of which 

 is straight, and of which the extremities are sharply turned upward. The 

 sides are not strongly arched, and the cross-section of a large specimen could 

 not be described as forming an open angle. The broadness of the head, the 

 marked difference in shape from that of C. mydas, and the concavity near the 

 lateral margins, could not have escaped the notice of the authors of the 

 Erpetologie Generate, if there were specimens of this species at hand. Their 

 description applies either to the species renamed by Dumeril and Bocourt 

 G. Agassizii, or to one much more closely allied to it than that described 

 above. If the separation of C. Agassizii from G. virgata of authors is right, 

 there exists a third species of Ghelonia in the Northwestern Pacific and 

 the northern part of the Indian Ocean. The specimens from which the de- 

 scription in the Erp. Gen. was taken were said to be from Teneriffe, Kio 

 Janeiro, Cape of Good Hope, New York, and the Indian Ocean, which dis- 

 tribution can leave little doubt that they were of more than one species. 



