108 



Of bones of the fore-arm, there may be one ; but the bones next in 

 size to the humerus look more like metacarpals or metatarsals. Two of 

 them were found together in position; and their relations were not like 

 those seen in the fore-arm of sea-turtles. They measure over seven inches 

 in length, and are strongly concave on their adjacent sides. One of them is 

 slightly concave on the outer side ; the other convex, the convexity being at 

 two-fifths the length from one end. The ends of both are a little expanded ; 

 and one end of one displays a double or trochlear extremity. The same end 

 of the other is injured by pressure. A still larger metacarpallike bone is 

 relatively more expanded at the ends. The articular surface of one of these 

 is wide at one end, and much narrowed at the other. The smaller bones, 

 undoubtedly phalanges, are six in number. They are quite slender, a little 

 expanded at the ends, and flat. 



Measurements. ' 



M. 



Length of the largest 0. 165 



Width of the largest at the extremity 0. 0C5 



Width of the largest at the middle 0.032 



Length of the longest of the pair 0. 180 



Width at the extremity 0.C50 



Width of the shaft 0.027 



Length of the phalange 0. 132 



Width at the extremity 0.032 



Width of the shaft 0.018 



Thickness of the shaft 0.011 



These measurements indicate, for the fore-limb, a total length of 4.52 feet 

 (l m .347) if proportioned as in Chelone; this would give an expanse of 11.3 

 feet. If, however, it was constructed on the plan of Sphargis, the expanse 

 would be nearer seventeen feet. 



Several instructive cranial bones were preserved. These are the maxil- 

 lary and distal part of tlie dentary of the left side ; the posterior part of the 

 left mandibular ramus; quadrate bones and adjacent pterygoids and squamo- 

 sal, one side with the columellar plate ; right postorbital bone and part of the 

 left; also, some probably hyoid elements. 



The maxillary bone and the dentary present a considerable extent of the 

 alveolar margin. This is remarkable in being thin, sharp, and elevated; 

 without horizontal portion. The former bone is but little incurved to the 

 premaxillary suture ; its anterior outline is elevated and vertical, the nostrils 

 entering opposite the probable middle of the orbit. The palatal plate of the 

 maxillary has no great antero-posterior extent, so that the inner nares are 



