90 ,R. S. Lull — New Tertiary Artiodactyls. 



passes into the faint ridge which delimits them. Distally 

 the horn becomes somewhat flattened transversely, but 

 dilated fore and aft, ending in a rounded terminus with 

 an elongated oval section. In Antilocapra, the horn-core 

 tapers to a point, the section being flattened with a 

 rounded hinder and sharp forward margin in a young 

 animal (ESL, male) and circular in an older male (Pea- 

 body Museum Osteological Collection No. 1518). 



In Aletomeryx there are faint longitudinal blood-ves- 

 sel depressions discernible in the older individual, No. 

 10734, but not in the younger. These impressions occupy 

 the same position as in Antilocapra, that is, on the outer 

 aspect, and lodged the artery to the corium or skin of the 

 horn, a continuation of the superficial temporal. In each 

 instance, the artery reaches the horn via the posterior 

 side of the orbit. The superior outline of the orbit is 

 continued upward in the form of a shallow tapering 

 groove 5 mm. or so on the outer aspect of the horn in the 

 male Aletomeryx. 



The horns of Dromomeryx have been described by both 

 Douglass and Scott. Scott's description follows: 3 



"The horns are very peculiar and quite unlike those of any 

 other known genus, fossil or recent. At the base the section 

 forms a spherical triangle, the three sides of which present for- 

 ward, backward and inward; the anterior face is concave, a 

 feature which is more marked in this species [Dromomeryx 

 (Blast -ornery x) antilopinus] than in [Dromomeryx] B. oorealis; 

 the other faces are convex. In the specimen before us the 

 horns are broken away about three inches above the base, but 

 Prof. Cope's numerous skulls of the larger species show that in 

 that form, at least, the horns were remarkably long, perfectly 

 simple and non-deciduous, none of them exhibiting any burr or 

 any tendency to branch. The young stages of Dicroceros have 

 a very similar unbranched horn, but the many known skulls of 

 Blast ornery x show that this simplicity is not a transitory char- 

 acter in this genus. Faintly marked grooves and ridges may be 

 seen on the surface of the horns, but their smoothness indicates, 

 with great probability, that they were permanently covered 

 with skin. The external angle of the base of the horn in [D.] 

 B. oorealis continued into a wing-like process which extends out- 

 ward behind the orbit. In the type of B. antilopinus this process 

 is broken away, but it can hardly have been so prominent as in 

 the larger species. As in Dicroceros and Antilocapra the horns 

 rise directly above the orbits, but are more erect than in the for- 

 mer genus." 



3 Scott, W. B., Trans. Amer. Philos. Soc, n. ser., vol. 18, p. 172, 1895. 



