/ 



R. S. Lull — New Tertiary Artio.dactyls. 91 



Douglass thus describes 4 the horns of Bromomeryx 

 borealis: 



"The horns are nearly circular in section above, but are tri- 

 angular just above the basal wing-like processes. The latter are 

 directed postero-externally. The antero-external faces are con- 

 cave and the outer borders thickened. ' ' 



Douglass restores the horn as tapering to a point, a 

 feature not evident from either description. 



In both species ofDromomeryx, therefore, the horns are 

 markedly different from those of Aletomeryx, in which 

 there is no trace whatever of the basilar wing-like pro- 

 cesses, evidently an utterly unique feature of the former 

 genus. Professor Merriam described to the writer orally 

 a specimen in the University of California collection in 

 which the horns are complete, tapering, and curve in- 

 ward toward the median line of the skull. 



Antilocapra is also unique in being the only living 

 ruminant with a deciduous and also a branched horn. 

 The skull before me (ESL, male), a relic of an early 

 expedition to Montana, is that of a young male wdiose 

 milk incisors and canines had not yet been shed, nor had 

 the third true molars fully erupted. The animal died dur- 

 ing the first week in July and upon maceration of the skull 

 a hairy skin was found beneath the horns. In Aletomeryx 

 the distal dilatation of the horn precludes the possibility 

 of a dermal horn, for growth on the part of the osseous 

 horn implies either a shedding of the covering as in Anti- 

 locapra or a shifting outw r ard of the entire structure, 

 additional horn material being secreted within and form- 

 ing ring-like outcroppings at the base of the older horn, 

 as in the other Cavicornia. It is difficult to see how with 

 a dilated osseous core either of these could be accom- 

 plished other than by a splitting of the tegumentary horn. 

 Then, too, the very faint character of the vascular im- 

 pressions wdiich are relatively much less distinct than in 

 Antilocapra, and, indeed, not discernible at all in the 

 younger male, is additional evidence for the absence of 

 any close fitting inelastic covering. The horns are not 

 antler-like, and hence could hardly have been comparable 

 to those of existing deer, except perhaps at the time the 

 antlers are forming and in velvet, when they may also 

 show somewhat dilated termini, as in the fallow deer, 

 comparable to the horn under discussion. 



4 Douglass, Earl, Ann. Carnegie Mus., vol. 5, p. 466, 1909. 



