102 Annals of the Carnegie Museum. 



close to the border of the glenoid cavity. The proximal end of the 

 radius is deeply grooved for the articulation of the humsrus and the 

 shaft is more suddenly constricted ^'' below the head and more rod-like 

 throughout than in Mesohippiis. Distally the articulations for the 

 scaphoid, lunar, and cuneiform are also more distinctly separated 

 by ridges than in the latter genus. The facst for tha cuneiform is 

 located laterally in the specimen under description. 



No. 2923 represents an animal somewhat heavier thaan the one de- 

 scribed above. The length of the tibia is completely represented, 

 and shows a stouter bone than in Epihippus parvus. The hind foot 

 was possibly shorter and stouter. The lateral digits are apparently 

 also slightly more reduced than in Epihippus parvus. 



31. Epihippus parvus Granger*^" (Plate XLII, Figs. 12-16). 



A specimen in the Carnegie Museum, No. 3397, referred to this 

 species, consists of the right upper cheek-dentition, the lower jaws 

 with Py-^, My-o of the left side; P^-g- and My of the right side; frag- 

 ments of the hind limb and the greater portion of the right hind foot. 



The specimen reveals an animal of slightly larger size than the type 

 of the species. The characters of the teeth agree very closely with 

 those of the type in the American Museum of Natural History, except 

 P~, which lacks the antero-internal tubercle, which is present in the 

 type. That this is a variable character in the species, it is cjuite 

 reasonable to suppose. A distinct feature is the relatively large size of 

 the tooth, when compared with P- of such a form as Orohippus 

 progressus Granger from the upper Bridger (see p. 250, and PI. XVIII, 

 Fig. I). 



The best preser\ed parts besides the upper and lower jaws are the 

 different portions of the hind limb. The pelvis is relatively slender, 

 the acetabulum well-formed, and relatively deeper than in Mesohippus. 

 The proximal end of the femur is broken off, but the distal portion 

 presents a slenderness which is proportional to the rest of the limb. 



The tibia and fibula are completely separated. The latter bone is 

 not represented, while the tibia is very nearly complete. There is a 

 prominent spine, separating the femoral articulations of the tibia, 

 which appears somewhat abnormal, esj^ecially in its anterior region. 

 The cnemial crest is sharp, not very much extended beyond the main 



^^ It is possible lliat this sudden constriction may be due, at least in part, to 

 crushing. 



6' Bttll. Amcr. Mjis. Nal. Hist., Yo\. XXIV, 1908, p. 258, PL X\'III, Fig. 3. 



