522 



University of California Publications in Geology [Vol. ll 



Specimen 20052 consists of a part of the beam, which divides into 

 two nearly equal branches diverging almost horizontally. Upon the 

 nearly even superior surface of the branches are a considerable num- 

 ber of small spikes or papillae. Of the two branches, one is projected 

 approximately in the plane of the flattened beam. The other branch 

 curves rather sharply away from this plane (fig. 1355). The branch 

 bending away from the plane of the beam is the smaller. A number 

 of the superior spikes or papillae bend out at a low angle from the 

 convex side of the curve formed by the two branches. It seems 

 probable that the plane of the beam was anteroposterior rather than 

 transverse to the skull, and that the papillae on the convex side of 

 the bow are on the outer or lateral, rather than on the inner side 

 of the horn. If the smaller of these two horizontal branches is the 

 anterior, this is the right horn. 



The spikes or papillae on the upper side of the horn are in two 

 rows. There are six on the concave side, and four on the convex side. 

 The inner six are arranged in three pairs. Of the outer four there 

 is a single large spike opposite the posterior inner pair and a similar 

 one opposite the space between the anterior and middle inner pairs, 

 and a pair of papillae arising from a common base opposite the mid- 

 dle inner pair. The inner papillae are nearly erect, excepting the 

 most anterior one. The papillae on the outer side are directed out- 

 ward at a low angle. Judging from the single specimen available, 

 the anterior branches of the right and left horns of this animal curved 

 in toward each other over the face, the other branches extended back- 

 ward and slightly inward, making a crown-like or- horseshoe-like 

 structure above the head. 



Specimen 20052 resembles most nearly the horn or antler of 

 Merycodus, which it also approaches in size, and to some extent in 

 the texture of the horn. It differs from Merycoclus in the form of 

 branching, and in the presence of the double row of superior spikes. 

 The texture of the surface of specimen 20052 differs somewhat from 

 that of any of the numerous Merycodus horns available from the 

 Barstow Miocene. It is possible that the contrast is due in part to 

 condition of weathering, but it seems partly due to difference in 

 structure. 



The peculiarities of specimen 20052 may be accounted for on the 

 assumption that it is a "sport" or "monstrosity" of Merycodus 

 necatus, a common form in the Mohave region. A large number of 

 Merycodus horns have been found in the Barstow, but on no other 



