Vol. 56.] 



ARISTOOESMUS RUTIMEYERI. 



631 



Radius. 



The articular part of the proximal end of the humerus is narrower 

 than the radial crest. The bone is flattened superiorly, with a 

 tendency to be concave from above downward ; and it makes an 

 angle of about 45° with the radial crest, which is of similar size 

 and form. The longitudinal lateral margin on the ulnar side of 



the bone is much 



Eig. 4.— Right fore-limb of Aristodesmus m °re concavely 



Kutimeyeri. (Nat. size.) excavated proxi- 



mally than the 

 radial side, be- 

 hind the talon-like 

 process. 



The entire hu- 



Humerus. mlSSiSf* , * 



merus is com- 

 pressed, so that 

 its lateral margins 

 are thin. The 

 compression and 

 the twist in the 

 bone are like those 

 known in Prot- 

 orosaurus, Dicyii- 

 odon, and Rhopal- 

 odon, though it 

 is more like 

 the humerus of 

 Echidna in the 

 expansion of its 

 proximal and dis- 

 tal ends. The 

 twist of the bone 

 makes the curved 

 lateral contour on 

 the radial side ap- 

 pear to be deeply 

 concave ; the con- 

 cavity on the ulnar 

 side of the bone 

 is deeply exca- 

 vated. 



The transverse 

 width of the mid- 

 dle of the shaft 

 below the middle 

 length of the bone is less than a fourth of the width of its extre- 

 mities. The distal expansion transversely is much more rapid than 

 the transverse expansion of the proximal end. The inferior distal 

 margin is nearly straight transversely, but notched external to the 

 radial articulation ; it is thin. The vertical lateral borders of this 

 expansion are nearly parallel. 



