AVillistox.] Mosasaurs. 155 



is preserved in this specimen. The .outer one is subround or 

 subquadrate, and articulates with the following bones, there 

 being no free border : radiale, mediale, medial distal carpal, 

 first and second metacarpals. 



Clidastes velox. The carpals of Clidastes are seven in number, 

 situated in two rows, and firmly articulated with each other 

 and the adjacent bones. They very much resemble the bones of 

 Mosasaurus. The largest is the radiale, an irregularly shaped 

 bone, and thicker than any of the others. Its thickest facet is 

 for articulation with the radius. Its rounded outer angle is free. 

 Its longest face, directed obliquely outward, is for articulation 

 with the first metacarpal. On the inner side there are two 

 facets, indistinctly separated, the proximal for articulation with 

 the mediale, the more distal one for the outer distal carpal. Be- 

 tween the mediale and the angle of the radius there is a short, 

 free, rounded border. The mediale is five-sided. Its shortest 

 side articulates with the radiale ; the longest, at the opposite 

 end, with the ulnare. Between these faces distally there are 

 three articular facets for the three distal carpals, the outer one 

 the longest, and meeting the middle in an angle. Proximally, 

 between the radial and ulnar facets, the border is free, concave, 

 and thinned, continuing the curve from the radiale to the angle 

 of the ulna, which the bone slightly touches. The ulnare is in- 

 distinctly five-sided, and is the second largest bone of the carpus. 

 The largest and thickest face articulates with the ulna ; the 

 shorter face, on the outer side, with the mediale. Internally, 

 the broad, rounded end has two facets, indistinctly separated, 

 for articulation with the pisiform and the fifth metacarpal. The 

 pisiform, an elongate bone, is inserted into the entering angle 

 between the ulna and the ulnare ; of the two proximal faces, that 

 for the ulnare is a little the longer. The distal extremity is 

 transversely convex, and is tipped with cartilage. The two 

 sides are parallel and free, the distal one shorter and thinner 

 than the proximal one. The distal carpals, three in number, 

 are all of nearly the same size and shape, the inner one a little 

 the largest. They are irregularly four- or five-sided. The inner 

 one articulates with the ulnare, the mediale and the second dis- 



