R. S. Lull — New Tertiary Artiodactyls. 95 



of the other crania because of conditions of preservation. 

 A similar foramen is shown by Douglass 5 and Scott 6 in 

 their figures of Dromomeryx, although its position is 

 lower on the skull. 



The nuchal crest is generally broken away in the skulls 

 before me. In the holotype, No. 10732, however, it is well 

 developed and overhangs the occiput, so that as preserved 

 it extends about 10 mm. beyond the vertical portion of 

 the occipital bone. To what extent this is exaggerated by 

 crushing, it is difficult to say. Herein again Aletomeryx 

 differs from Antilocapra and agrees with Dromomeryx. 

 The profile of the skull shows a well rounded brain-case, 

 somewhat arched nasals, and a distinct concavity between 

 the orbits just behind the fronto-nasal suture. This is in 

 agreement with Antilocapra and to a less extent, perhaps, 

 with Dromomeryx, in which the profile is more nearly 

 straight except for the concavity between the orbits in 

 D. borealis. Scott makes no mention of this cavity in 

 D. antilopinus, but speaks of the "straight upper surface 

 of the skull." 



In Aletomeryx, there lies between the horns a low but 

 distinct median protuberance corresponding to the fron- 

 tal eminence of the ox. In Antilocapra this frontal emi- 

 nence is broader, and in the old male No. 1518 forms a 

 transverse ridge connecting the bases of the horns. This 

 ridge lies just behind the frontal depression. 



The parietal region of the skull, as seen in profile, is 

 somewhat similar in Aletomeryx and Dromomeryx anti- 

 lopinus, curving downward somewhat less than in Antilo- 

 capra. Douglass restores this portion of the skull of 

 D. borealis as though it were nearly straight. His 

 evidence for this is not apparent, and it may have been 

 more as in Scott's specimen and therefore in closer agree- 

 ment with Aletomeryx. 



The orbit is somewhat irregular in outline, as shown by 

 the figure, while that of Antilocapra and of Dromomeryx, 

 to judge from Douglass' figure, is more nearly circular. 

 Scott speaks of the orbit in D. antilopinus as being much 

 lower down and farther forward in the face than in Anti- 

 locapra, its upper border not projecting above the 

 superior contour of the cranium. This is not entirely 

 true of Aletomeryx, for while the postorbital region of 

 the skull is relatively longer than in Antilocapra, the 

 orbit is relatively high and the upper margin does extend 

 above the superior contour of the cranium. 



5 Op. cit., pi. LIX. 6 Op. cit., pi. VI. 



