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University of California Publications in Geology [Vol.9 



The horn-eore of this specimen represents one of the most remark- 

 able types yet discovered, and differs widely from that of any other 

 form, either living or extinct. Looking at it in side view it has the 

 appearance of a double horn growing from a single broad base (fig. Id). 

 The larger posterior prong, which reaches to a height of 65 mm. 

 above the dorsal rim of the orbit, is more or less cylindrical, though 

 somewhat flattened on the anterior face, and tapers evenly from the 

 point of separation from the smaller anterior prong. The latter does 

 not have the usual appearance of a fork, but grows out parallel to the 

 larger prong from a common broad base about 15 mm. high, which 

 gives the impression of a growing together of the basal portion of two 

 horns rather than the broad base of a single horn which has two forks. 

 The anterior prong is not only shorter but of much smaller calibre 

 than the posterior prong. It is triangular in cross-section, having 

 a broad flat posterior face, the apex of the triangle pointing anteriorly 

 (fig. lb). Prom the posterior view the anterior prong does not appear 

 at all (fig. la). Figure lc shows the appearance of the horn-core look- 

 ing- straight down at it from above, and makes clear the relation of 

 the two prongs to each other. Prom what sort of a horn-core this very 

 unusual type might have been derived cannot be suggested with any 

 reasonable assurance as yet. Its relation to the horn of Antilocapra 

 is also doubtful. While it may represent an entirely independent off- 

 shoot from a common ancestor, it may also be in the direct line of 

 descent of Antilocapra. In fact, the peculiar sword-like shape of the 

 horn-core of the pronghorn antelope can more easily be imagined to 

 have developed from the type of horn found in Capromcryx minor 

 than from any other known kind of horn-core, merely by a further 

 growing together of the apposed faces of the two prongs. The form 

 of the horn sheath, with its long posterior and short anterior prong, 

 might be looked upon as suggesting an ancestral condition in which 

 the horn-core was also forked. There is no other known case in which 

 a simple horn-core possesses a forked sheath. 



JAWS AND DENTITION 

 Specimen no. 20032 is a fragment of the right maxillary bone with 

 M 1 and M 2 in place. These teeth resemble their counterparts in 

 Antilocapra very closely, the only difference in form being in the 

 slightly better development of the outer styles. These teeth of 

 Capromeryx are almost exactly two-thirds the size of the correspond- 

 ing ones of Antilocapra. 



