HISTORY OF THE ARTIODACTYLA 417 



of it have been found in the Pleistocene cave-deposits of Cali- 

 fornia. This animal is a member of the true antelope family 

 (Antilopidse) and belongs to the chamois group of mountain- 

 antelopes; it has no near relatives among other American 

 mammals, living or extinct. 



The Prong Buck, or Prong-horned Antelope {Antilocapra 

 americana), occupies a very isolated position, so much so that a 

 distinct family, the Antilocapridae, has been created for its 

 reception. It differs from all other Cavicornia in having a 

 branched horn, though the bony core is simple, and in an- 

 nually shedding and renewing the horny sheath ; the horn is 

 directly over the eye ; there are no dew-claws and all traces of 

 the bones of the lateral digits have completely disappeared. 

 The grinding teeth are thoroughly hypsodont. The genus 

 occurred in the older Pleistocene, where it was associated with 

 the last of the fdeer-antelope, or jMerycodiis series {\Capro- 

 meryx), and which, so far as it is known, would seem to con- 

 nect the two families, though this is doubtful. A middle 

 Miocene genus {^Dromomeryx Fig. 128, p. 237) would be a more 

 probable ancestor of the Prong Buck, if it were not for the long, 

 unfilled gap of the upper Miocene and the whole PUocene. 

 \Dromomeryx had erect horn-cores placed directly above the 

 eyes as in the modern genus, but low-crowned grinding teeth ; 

 it was the most ancient American cavicorn yet known. It 

 remains to be determined by future exploration, whether this 

 middle Miocene genus was actually the ancestor of Antilocapra, 

 or merely an anticipation of it. 



In the lower PUocene have been found the remains, very 

 incomplete, of several antelopes, which appear to have been 

 immigrants from the Old World, but are too imperfectly known 

 for any definitive reference. One resembles the flat-horned, or 

 goat-horned, antelopes of the European Miocene and Pliocene. 

 Others had spirally twisted horns Uke those of the Recent 

 strepsicerine, or twisted-horn antelopes of Africa and Asia, but 

 may, nevertheless, be referable to the Antilocapridse.. 



2 E 



