330 University of California Puhlications in Geology [Vol. 12 



PLIOHIPPUS FEANCESCANA MINOR, n. subsp. 

 Folder 3, figure 3 



Type. — Four closely associated upper cheek teeth, Univ. Calif. Coll. Vert. Pal. 

 23263, 23264, 23266, 23267 (folder 3, and figs. 39a-39b), representing( ?) Pi and 

 Ml of the left side, P^ and Mi of right side, Univ. Calif, loc. 3236. 



Bef erred viaterial. — To this species are referred an upper P-(?), no. 23275 

 (figs. 38a-38b; folder 3, fig. 4, loc. 3264; a lower tooth, no. 23274 (figs. 40a- 

 40b), loc. 3258; a small set of incisors in a portion of a premaxillary, no. 23347 

 (figs. 41a-41b), loc. 3256. All in Univ. Calif. Coll. Vert. Pal., all Univ. Calif, 

 localities. 



Characters. — The type is characterized by: (1) the relatively small 

 size of the teeth and the marked lightness of the styles; (2) the very 



40a 40b 



Figs. 40a and 40&. PlioMppus francescana minor, n. subsp. Pj, no. 23274. 

 Fig. 40a, occlusal view, X 1; fig. 40b, outer view, X %. San Timoteo beds, 

 California. 



slight degree of anterior projection of the protocone, which is very 

 slightly grooved on the inner surface in the premolars; (3) the con- 

 striction of the postprotoconal valley of the molars; (4) the narrow 

 and relatively simple bordered fossettes; (5) the small dimensions of 

 the primitively formed, referred lower tooth; (6) the .small size of the 

 referred premaxillary and incisors. 



Description. — The upper cheek teeth of the type specimen (see 

 folder 3, figs. 3a-3e) are considerably worn, with resulting very short- 

 crowned appearance (they are in about the condition of wear of the 

 P. francescana, type and of the older Bautista series (see folder 3, 

 fig. la; folder 2, fig. 3a-). They are noticeably small, and are only 

 moderately heavily cemented. The mesostyle is deep and remarkably 

 narrow. The protocone is thick and rounded, with moderate antero- 

 posterior diameter; in the premolars the inferior border is very 

 slightly indented ; in the molars it is elongated and somewhat flattened. 

 The postprotoconal valley is comparatively narrow in the premolars, 

 the walls are appressed in the molars where the anterior accessory fold 

 of the valley is absent. The fossettes are extremely narrow, and have 

 noticeably simple borders. The exterior wall of the paracone is flat. 



