R. S. Lull — New Tertiary Artiodactyls. 113 



ever, in individuals in the fossil. In general the prong- 

 buck sacrum does not taper so much behind the wings 

 as do those of Aletomeryx. This greater tapering in the 

 fossil may again be indicative of greater primitiveness. 

 The measurements follow : 



Aletomeryx Antilocapra 



m. m. Ratio 



Length over all -0645 -1000* 1-55 



Height over all -0285f -0570 2-00 



Breadth across wings 0605 1000 1.65 



Length of centrum I 0170 -0250 147 



Length of centrum II 0155 -0212 1-36 



Length of centrum III 0130 0200 1-54 



Length of centrum IV -0138 -0180 1-30 



Width, posterior end -0170 -0258 1-52 



Av. 155 



* Four saerals only. 

 t Somewhat crushed. 



Caudal vertebra. — No trace of Aletomeryx caudals has 

 been found. It is fair to assume, however, that the tail 

 approximated the average ratio of the vertebral column, 

 about 1-40. Of the caudal vertebrae of Antilocapra, No. 

 180, but two remain. The male, No. 1518, a smaller 

 animal, has a tail 425 m. long, while the sacrum measures 

 but -085 m. The sacrum of the mounted Aletomeryx 

 measures -063 m. If the ratio of tail to sacrum were 

 constant, the rule of proportions would give a length of 

 •0926 m. for that of Aletomeryx. This is probably a mini- 

 mum estimate, as caudal reduction is to be expected in 

 these forms with evolutionary advance. 



Ribs. — A number of ribs are present, none of which, 

 however, is complete throughout its entire length. They 

 have no outstanding differences with those of Antilo- 

 capra except perhaps a less width. At any rate, there 

 seem to be fewer wide ribs in the fossil, but to what ex- 

 tent this apparent difference is due to imperfection of 

 the material is not so clear. 



Sternum. — Three sternal elements are present, of 

 which two may pertain to the manubrium ; one certainly 

 does. This seems to lack the anterior extremity, other- 

 wise it differs from that of Antilocapra in the greater 

 relative volume at mid-shaft, and if correctly oriented, in 

 possessing a dorsal median groove where the prongbuck 



