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University of California Publications in Geology 



[Vol. 12 



accessory plications, especially those of little to moderately worn teeth. 

 The incisors are large and still deeply cupped (fig. 25) ; the strongly 

 concave outer edge of each incisor overlaps the convex inner edge of 

 the adjoining tooth. 



The loxcer dentition (figs. 19-24) is of a long and rather narrow- 

 crowned type. The fold of the metaconid-metastylid column is broad, 

 deep, and symmetrically V-shaped, becoming more open and asym- 

 metrical in worn specimens through the simultaneous elongation of 



Fig. 25. Equus bautistensis, n. sp. Premaxillary with incisor teeth, no. 23348, 

 X Bautista beds, California. 



the metaconid. The inward folding between the protoconid and 

 hypoconid is sharp, and deepens from the premolars to M,. In a 

 worn series (fig. 19) the fold is slightly broader and rounder. In the 

 molars the fold only meets the mouth of the metaconid-metastylid 

 column {versus its much greater depth and breadth in old specimens 

 of E. caballus). The inner wall of the hypoconid of is considerably 

 crinkled, as in E. caballus. The outer faces of the protoconid and 

 hypoconid are markedly flattened, especially in the premolars, perhaps 

 even more so than in E. caballus. The anterior portion of the entoconid 

 resembles that of E. caballus, and the inward extent of the parastylid 

 is similar. 



The mandible is very broad (fig. 24), measuring 101.6 mm. in 

 depth in the region of P-. The inferior border is not concave as in 

 E. caballus, nor does it show the deep concavity anterior to the angle 

 of the jaw seen in E. occidentalis of Rancho La Brea. It resembles 

 more closely the mandible of E. scotti.^- 



The premaxillary is expanded in the region of the incisors, and 

 appears to be of rather elongated proportions, pointing to a propor- 

 tionately long-snouted form. 



12 Gidley, J. W. Bull. Am. Mus. Nat. Hist., vol. 13, p. 114, fig. 3, 1900. 



