JUNE, 1896. SKELETON OF TOXOCHELYS HAY. 105 



lack of a parieto-squamosal arch and in the occurrence of a well 

 developed squamosal bulla, neither of which things is probable. 



In its general form the skull of Toxochelys is more like that of 

 the Cheloniidce than it is like that of the Chelydridce. As to the 

 hinder part, there is no question. Anteriorly the snout is broad and 

 rounded, not acuminated, as it is in the Chelydridce. The large 

 orbits also remind us of the sea-turtles. The skull appears to have 

 been rather depressed, as in Thalassochclys; not high, as in Chelonia. 

 The lower jaw figured by Professor Cope resembles that of Chclydra; 

 but is not hooked, and has no decided cutting edge. 



Professor Cope has figured the coracoid of his specimen. In 

 form and proportions it closely resembles that of Chelonia. Its length 

 was 250 mm. The coracoid of a specimen of Chelonia, whose shell is 

 i metre long, is 300 mm. in length and the ramus of the lower jaw is 

 150 mm. Since the proportional lengths of the coracoids in Chelydra 

 and Chelonia are about the same, the shell which belonged to Professor 

 Cope's specimen was probably about 825 mm. long, and the head was 

 somewhat larger than that of Chelonia. 



' Dr. Joseph Leidy, in his "Contributions to the Extinct Vertebrate 

 Fauna of the Western Territories," page 269, plate 36, 1873, has de- 

 scribed and figured some turtle bones. These he refers with some 

 doubt to Professor Cope's genus Cynoccrcus. A comparison of Dr. 

 Leidy 's figures 20 and 21 with Professor Cope's figures of the coracoid 

 of Toxochelys convinces me that they belong to the same animal. Be- 

 side the portions of the two coracoids, Dr. Leidy possessed a portion 

 of* the scapula, a complete femur, and the proximal end of the 

 humerus. Notwithstanding that these bones are somewhat fragmen- 

 tary and more or less flattened by pressure, we may learn something 

 from a comparison of them with the corresponding bones of the 

 Chelydridce and the Cheloniidce. 



One character which as much as any other distinguishes the sea- 

 turtles from other turtles is the great development of the anterior 

 limbs. In most turtles the humerus has about the same length as 

 the femur. This is true of the Chelydridce and such habitual swimmers 

 as the Trionychidce. But in Chelonia the femur is only two-thirds the 

 length of the humerus. Now, it is not wholly certain that the humerus 

 and the femur in Dr. Leidy's hands belonged to the same skeleton, 

 but he supposed that they did. If so, then the humerus of that 

 animal must, on proper estimate, have been nearly as much longer 

 than the femur as that bone is in Chelonia. This deduction, taken in 

 connection with Professor Cope's statement that the phalanges are 

 flattened, compels us to regard Toxochelys as a true sea-turtle, as does 

 also the fact that it is found so abundantly in the Cretaceous deposits 

 of Kansas. 



