R. 8. Lull — New Tertiary Artio dactyls. 117 



buck the groove is lacking, as the inner ridge is obsolete. 

 Neither the ox nor the modern horse exhibit a grooved 

 olecranon, but the ancestral horses Mesohippus and Mio- 

 hippus do, as do also the dog and sometimes the cat. This 

 character therefore seems to be a primitive one, and 

 hence its presence in Aletomeryx does not exclude the 

 genus from the direct ancestry of Antilocapra. The 

 shaft of the fossil ulna is not so thin relatively as in the 

 prongbuck, nor does its outline suggest such a degree of 

 reduction of the distal portion as in the modern animal. 

 The measurements are : 



Aletomeryx Antilocapra 



m. m. Ratio 



Length over all -1490* -2480 1-66 



Prox. (olecranon) ant. -post. diam. . -0187 -0290 1-55 



Prox. (olecranon) transverse diam. . -0085 -0134 1-57 



Mid-shaft, ant.-post. diameter -0057 -0060 1-05 



Mid-shaft, transverse diameter -0014 -0028 200 



Distal end Not preserved. 



* Estimated. 



Av. 1-56 



Car pals (figs. 16, 17). — All of the carp alia are present. 

 They differ only in minor details from those of the prong- 

 buck, as the figures show. 



Metacarpals (^g, 17). — Metacarpalia I, II, III, and IV 

 are present, the second and third being united into a 

 cannon-bone which again resembles that of the antelope 

 very closely, differing therefrom in dimensions and in the 

 very distinct impression of metacarpal V on the proximal 

 half. The inner side of the cannon-bone shows no such 

 impression. Below, the bone is rounded, nevertheless 

 both lateral digits were present, as they are preserved in 

 the material. To what extent, therefore, the lateral 

 metapodials were developed it is difficult to say, as not 

 more than an inch of the distal end of the inner one is 

 preserved, and merely the articular extremity of the 

 outer. There are impressions of both lateral metacar- 

 pals on either side of the distal extremity. No such im- 

 pressions are visible in the prongbuck, where the lateral 

 toes are entirely lacking. 



The measurements of the left fore cannon-bone are : 



