Williston.] Mosasaurs. 185 



river, Graham county, Kansas, May 27, 1875. Under surface 

 of right fore paddle, sketched in original position, natural size. 

 Size of head, twenty-three inches from tip of snout to occipital 

 condyle. Scapula opposite sixth cervical vertebra (measure- 

 ments accurate). No. 68." The specimen is at present pre- 

 served in Yale museum under the above number, and the 

 accuracy of the drawing may be determined whenever the 

 material in that collection is studied. Measurements of every 

 bone, and the distances between the adjacent ones were given 

 in the drawing. 



The drawing is especially valuable as showing the natural 

 position of the digits and their relations to each other. The 

 carpal bones have been partially dislodged, and the four inner 

 metacarpals somewhat disturbed. At the tip of the third 

 finger there was a small oval ossicle, and at the end of the 

 radius a small nodule which was marked " sesamoid? ". It was 

 evidently cartilaginous. 



By comparison with Marsh's figure of his Platecarpus simus, 

 distinct differences will be seen in the shape of metacarpals. 

 These shapes are observed in the material in our collection 

 referred to P. coryphaeus. It seems evident from the drawing 

 that there were at least four phalanges in the first finger, six 

 in the second and third, five in the fourth, and four in the fifth. 



The size of the head, as compared with the paddle, it is seen 

 is very small. The length of the paddle as drawn w T as twenty- 

 nine inches, and it was at least two inches longer ; that is, the 

 proportion was as twenty-three to thirty. In Platecarpus cory- 

 phseus it was as twenty-one to about twenty-three ; in Clidastes 

 relax, as fifteen to about ten ; in Tylosaurus proriger, as thirty-six 

 to twenty-four. 



The following measurements of the types by Cope agree with 

 the specimens in our collection : 



" Quadrate greatest length 99mm. 



Anterior dorsal, length of centrum 59 



Posterior dorsal, length of centrum 55 



Scapula, length ... 1 145 



Humerus, length 154 



Radius, length 115 



