112 - R. S. Lull — New Tertiary Artiodactyls. 



Aletomeryx Antilocapra 



m. m. Eatio 



Centrum, length -0250 -0340 1-36 



Centrum, height, anterior -0140 -0218 1-55 



Centrum, width, anterior -0185 -0220 1-19 



Height over all -0373 -0707 1-89 



Width over transverse processes. . . -0800* -1070 1-34 



Av. 1-46 



Estimated. 



Lumbar VII. — The most remarkable feature of this 

 bone is the relative length of the centrum, which is -028 m. 

 long compared with -0315 for Antilocapra, a ratio of 

 but 1-12 as compared with 1-36 for the third lumbars. 

 This w r ould seem to be a more primitive feature. The 

 condition of the bone renders other over-all measure- 

 ments of little value. 



The dimensions are: 



Aletomeryx Antilocapra 



m. m. Eatio 



Centrum, length -0280 -0315 142 



Centrum, height -0122 -0184 1-51 



Centrum, width -0195 -0264 1-36 



Av. 1-33 



Sacrum (fig. 13). — Several sacra are present, none of 

 which consist of more than four vertebrae. In the two 

 specimens of Antilocapra before me, however, there are 

 five. This number may be due to the coalescence of the 

 anterior caudal. Some of the fossil sacra must have per- 

 tained to animals of equivalent age, so that the four-ver- 

 tebrae condition may also be looked upon as more 

 primitive. In the male prongbuck No. 1518, the summits 

 of the sacral spines are all free, w r hile in the large female, 

 No. 180, they are coalesced and the third and fourth are 

 broadened out laterally as w T ell. In all the Aletomeryx 

 sacra there is a coalescence of the first tw r o or three 

 spines to form the median sacral crest, with somewhat 

 broadened summits. The posterior centra are relatively 

 broader and flatter than in Antilocapra and the inter- 

 central (ventral sacral) foramina have less fore and aft 

 extent. In both genera there is a very rapid narrowing 

 of the sacrum from the wings backward, variable, how- 



