236 BULLETIN 16 9, UNITED STATES NATIONAL MUSEUM 



rises toward the protocone apex at the inner end and terminates in a 

 definite point, a rudimentary hypocone on the posterior protocone 

 slope and near, but separate from, the protocone tip. M^ is oval, 

 with rounded comers, and is reduced but much less so than in E. 

 inaeguidens. It has a vestigial but distinct metacone. 



The lower canine is known only from its single, cyhndrical root, 

 which indicates a small tooth (but larger than Pi) only slightly 

 procumbent. Pi has one small root and a slightly procumbent and 

 recurved simple crown, excavated on the posteromternal face. 

 P2 is considerably larger, 2-rooted, and with a single distinct heel 

 cusp. P3 is transitional to P4 in structure, with the heel considerably 

 expanded and a curved crest and excavation at the anterointernal 

 angle. P4, although sharply distinct from the molars, is more nearly 

 molariform than in any other species referred to this genus. There is 

 a low distinct metaconid on the posterointernal protoconid slope, at 

 about two-thirds of the distance from the base to the apex of the crown. 

 The anterointernal protoconid slope is excavated, and the anterior 

 protoconid crest curves inward and then posteriorly around it, gener- 

 all}'' without forming a cusp but in a few specimens with a very rudi- 

 mentary and low paraconid. The talonid has a slight crest ending 

 in a cusp at the posterior margin, somewhat external to the midline, 

 with a vague, open internal basin and a small posterointernal cuspule. 



Ml has the protoconid and metaconid opposite, the metaconid 

 slightly the larger of the two. The paraconid is distinct, fully 

 internal, partly connate with the metaconid, and smaller and lower 

 than the latter. The talonid is nearly as high as the trigonid and is 

 well basined, but with the basin open in a narrow notch between 

 entoconid and metaconid. The hypoconid is large, distinct and 

 crescentic. The small hypoconulid and larger and equally high 

 entoconid are poorly separated. When quite unworn, three small 

 cuspules are seen, one on the anterior hypoconid wing, one on the 

 posterior metaconid slope, and one on the anterior entoconid crest. 

 The talonid is wider than the trigonid. M2 is similar to Mi, but the 

 trigonid is larger, absolutely and relatively, and is as wide as or wider 

 than the talonid. The entoconid is reduced in size, in height, and in 

 distinction and the talonid basin more open. M3 is reduced, the 

 trigonid decidedly the widest part of the tooth, the entoconid indis- 

 tinct, and the hypoconulid large and sharply projecting as a well- 

 defined spur. 



U.S.N.M. no. 9686 preserves dm4. Its talonid closely resembles 

 that of Ml but is smaller. Tlie trigonid is much more elongate and 

 narrow than on the permanent molars, and the paraconid is larger 

 and well separated from the metaconid. 



The horizontal ramus is slender, with a long symphysis, which 

 seems not to have fused even in old age. The posterior mental 



