PLATE 32 



PREORBITAL FOSSAE IN H1PPARION FROM SOUTH DAKOTA AND TEXAS. 

 COMPARISON OF ANTERIOR PORTION OF SKULL IN THREE AMERICAN SPECIES. 



All figures one-half natural size. 



Little White River, So. Dak. Lower Pliocene 1. Hipparion whitneyi Gidley, type, Am. Mus. 9815. Lachrymal fossa 



shallow, broad; no malar fossa. 

 Llano Estacado, Texas 2. Hipparion lenticulare Cope, neotype (Gidley), Am. Mus. 10854. 



Lachrymal fossa deep, restricted, anterior in position; no malar 



fossa. 



Little White River, So. Dak. " " 3. Hipparion gratum Leidy, neotype (Gidley), Am. Mus. 10863 



(reversed in drawing). Lachrymal fossa shallow, restricted, 

 anterior in position; malar fossa vestigial. 



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