1921] Prick: Faunas of Bautista Creek and San Timoteo Caiion 327 



Pj, anteroposterior diameter 31,5 mm. 



Pj, transverse diameter 20 



Pj, length of metaconid-metastylid column 18.8 



Mj, anteroposterior diameter 26 



Ml, transverse diameter 17 



M;, length of metaconid-metastylid column 15.2 



M2, anteroposterior diameter 28.8 



Mj, transverse diameter 16.5 



Limh elements. — A metacarpal (pi. 46, fig. 1), with the first and second 

 phalanges, no. 23521, loc. 3255. A metacarpal, no. 23474, loe. 3260 (pi. 46, fig. 3); 

 proximal and distal portions of a metacarpal no. 23475, associated with proximal 

 portions of a first and third phalanx, no. 23500, loc. 3254 (pi. 46 fig. 2); meta- 

 tarsus no. 23476, loc. 3215 (pi. 46, fig. 4); proximal portions of first phalanges, 

 nos. 24230, 24231 (pi. 46, fig. 5); the top of a ealcaneum, no. 23764, loc. 3249 

 (pi. 46, fig. 6). All specimens in Univ. Calif. Coll. Vert. Pal.; all Eden localities. 



A metacarpus with first and second plialanges was found in prox- 

 imity to the four molars of Pliohippivs francescana minor, but it is 

 believed to be too large comparatively for reference to the small species, 

 and together with the balance of the material, which is all of pro- 

 portionate size, is tentatively placed under the larger form. A second 

 metacarpus and portions of a third, associated with pieces of phalanges 

 and pedal bone, agree specifically with the first. The unciform facet 

 is well developed, the bones being those of a monodactyl horse in all 

 particulars. Compared to the generally larger E. hautistensis (pi. 45), 

 the metacarpiTS is slightly longer and lighter, as are the associated 

 podial elements. The metatarsus is alone represented by the proximal 

 end of a single specimen, and appears fully as heavy as the referred 

 metacarpus. The cuboid facet is proportionately smaller than in 

 E. hautistensis. The posterior elements are all somewhat lighter than 

 those of E. hautistensis. 



Comparisons. — In size the P- of the series nearly ec(uals that of 

 the type specimen of Equus giganteus,-^ which, as figured by Gidley, 

 strongly suggests a tooth of the P- position. The long anterior pro- 

 jection of the elongate protocone and the complicated lake borders 

 of E. giganteus, however, are unmistakably of the genus Equus. It 

 is of great interest to find a Pliohippus dentition of as large size as 

 that suggested by this large tooth of a later Equus. 



The dentition referred to Pliohippus francescana differs from that 

 of Equus hautisten.ns in: (1) its larger size and heavier styles; (2) 

 the remarkable shortness as well as the circular section and unindented 



2-* Gidley, J. W. Tooth Characters and Revisions of the North American 

 Species of the Genus Equus. Bull. Am. Mus. Nat. Hist., vol. 14, p. 137, 1901. 



