. Carnegie Institution of Washington publication. '''IdfPt \. Figs. 2:1 232.—Portkochelys laticeps. Skull of tvpe. X] 2; 1. Upper surface. 232. Palatal surface. extent of the roof can not be determined; but it was probably as extensive as in Toxochelys. The bones of the upper surface of the skull are much roughened, as in Chelydra. The palatal surface of the skull is shown in fig. 232. The cutting-edge of the maxilla is deeper than in Toxochelys latiremis, and its depth increases toward the jugal bone. The palatal surface of the bone, 10 mm. wide in tront, increases to 20 mm. at the hinde
. Carnegie Institution of Washington publication. '''IdfPt \. Figs. 2:1 232.—Portkochelys laticeps. Skull of tvpe. X] 2; 1. Upper surface. 232. Palatal surface. extent of the roof can not be determined; but it was probably as extensive as in Toxochelys. The bones of the upper surface of the skull are much roughened, as in Chelydra. The palatal surface of the skull is shown in fig. 232. The cutting-edge of the maxilla is deeper than in Toxochelys latiremis, and its depth increases toward the jugal bone. The palatal surface of the bone, 10 mm. wide in tront, increases to 20 mm. at the hinder end. The masti- catory surface extends over on the palatine and is markt internally by a rough ridge. Trans- versely the surface is slightly concave. The choanae are not encroached on by plates from the vomer and palatines, as they are in the Chelonndae, but lie well forward in a shallow fossa. They are separated bv the vomer, which is wide anteriorly, narrow between the choanae, and develops a sharp ridge on its palatal surface. As in Chelydra, each pterygoid developt a strong lateral process, against which the inner surface of the dentai)- workt. The width of the pterygoids, where narrowest, is 30 mm. The quadrates are notcht behind for the passage of the columella, as in Toxochelys. Of the mandibles only the united dentaries are pres- ent tig. 1^,7,). They are very heavy and strong bones. The masticatory surface is somewhat concave both trans- versely and longitudinally, and is bounded internally along the anterior half by a rough ridge. At the sym- physis the two ridges unite and run to the front of the law. This masticatory surface is, in front, only about half as wide as is the symphysis itself; but it widens backward and overhangs the inner lower border of the jaw. The coronoid process is considerably elevated. The carapace (plate 31, fig. 2; text-rig. 234) is now very flat. How deprest it was during life it is impossible now to sav; but it probably had no great elev
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