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University of California Publications in Geology [Vol. ll 



or two genera are represented by this range, which seems also to 

 be indicated by a difference in form. 



The proximal end of metatarsal III, no. 21198, in its dimensions 

 resembles that of Hipparion, as figured by Weithofer. 42 In specimens 

 of metatarsal III available from Ricardo the middle portion of the 



211 



Fig. 211. Herycochoerus? (Pronoviotherium?) calif ornicus, n. sp. Skull, type 

 specimen, no. 21351, ventral view, X ] 4- Ricardo Pliocene, Mohave Desert, Cali- 

 fornia. 



proximal face is more deeply indented than in metapodials of the 

 European form, and there is a separation of the posterior region of the 

 ectocuneiform facet as a distinct lunate articular area. In Hipparion 

 the posterior area is not separated from the anterior. 



The proximal face of metacarpal III in no. 21202 (fig. 194) seems 

 to differ from that of Hipparion in possessing a small notch in the 

 middle of the unciform facet. The dimensions are near those of the 

 European form. 



The slender proximal phalanx from Ricardo seems more slender 

 than in Hipparion forms of the Old World and approaches the type 

 of Pliohippus. In some cases, proximal phalanges of Hipparion may 

 be heavier than the wider form from Ricardo seen in no. 21197 

 (fig. 196). 



4- Weithofer, A., Beitriige zur Kenntniss der Fauna von Pikermi bei Athen, 

 Beitr. Palae. Geol. Oest-Ung., Bd. 6, Taf. 13, figs. 14 and 15, 1888. 



