182 



MAEINE EEPTILES OF THE OXFOED CLAT. 



bears a roughened surface for muscle-attachment, and its ventral surface towards its 

 upper end is likewise roughened (text-fig. 90, C, m.r.). The great distal expansion 

 bears two large facets for union with the radius and ulna : of these surfaces that for the 

 radius is the larger and is slightly concave, while that for the ulna is usually straight or 

 very gently concave ; the two make a very obtuse angle with one another. In some 

 cases there may have been a small postaxial accessory ossicle articulating with the 

 humerus. 



The radius (?"., text-figs. 90, 91) is very large and of peculiar form : this shape being 

 already marked at a very early age (text-fig. 90, A, B) is of considerable value in 

 determining as belonging to this genus very young individuals in which most of the 



Te3t-fig. 90. 



mcY. 



Proximal portions of fore paddles of Cryptocleidus oxoniensis : A, left fore paddle of very young individual 

 (E. 2417, ^ nat. size) ; B, left fore paddle of older individual (E. 2416, 1 nat. size) ; C, right 

 fore paddle (ventral face) in which ossification is complete (E. 2412, -i nat. size). In A the carpals 

 are not in place. 



a.o., accessory ossicle; ^., head of humerus; htim., humerus; int., intermedium; tkc F., fifth metacarpal ; 

 m.r., ridges for muscle-insertion ; r., radius ; rad., radiale ; w., ulna ; idn., ulnare ; iu., tuberosity of 

 humerus. 



Other characteristics are not yet developed. In the adult the humeral border is slightly 

 convex ; its outer (preaxial) border is greatly elongated, convex above and concave below. 

 The ulnar border is short and straight or slightly concave, while the distal border is 

 also slightly concave and articulated with the radiale, with, in some cases, a short 



