272 Annals of the Carnegie Museum. 



very different, except in size, from the corresponding parts of the type 

 of licholeptus breviceps, which was found about a mile farther south, 

 apparently at a little lower level. 



Generic Characters. — (i) Deciduous teeth brachyodont ; (2) per 

 ?nanent teeth somewhat hypsodo?it ; (j). both permanent and temporary 

 teeth without cement on crowns ; (4) metaloph on the upper permanent 

 teeth not united with ectoloph ; (5) protoconule small ; (<5) melaconule 

 faintly i?idicated on the metaloph; (7) hypo style moderately large tri- 

 angular and having a central pit ; (8) limbs long; (p) metapodials 

 unusually long and slender ; {10) ungual phalanges long and narrow; 

 (77) metatarsals nearly the length of the radius. 



The zygomatic arch is slender and the orbit large. The infraorbital 

 foramen is over the third temporary molar. The first temporary molar 

 is one half of the width and a little over one half of the length of the 

 second temporary molar. The latter tooth has a small median internal 

 pillar between the two internal cusps. The third and fourth tempo- 

 rary molars are nearly equal in size and their antero-posterior and 

 transverse diameters are nearly equal. The protoloph and metaloph 

 are connected with the ectoloph. The hypostyle is large. The first 

 and second permanent molars are nearly equal in size. Their ecto- 

 lophs are oblique, the anterior portion of the tooth being broader than 

 the posterior portion, and the protoloph being larger than the ectoloph. 

 The cross-crests are not connected with the external crest except at the 

 bases. The parastyle is small and its inner portion is a sharp vertical 

 ridge. The mesostyle is low and thin and there are faint median ex- 

 ternal ridges on the paracone and metacone. The protoconule is 

 small but well defined, but the metaconule is only faintly indicated 

 by a minute protuberance on the top of the metaloph. 



The first lower deciduous molar is a little more than one-third the 

 length of the second. It had one simple cusp and a low heel. The 

 second temporary molar is the longest tooth in the mandible. There 

 are cingula on the outsides of the third and fourth deciduous molars. 

 The first permanent lower molar retains the pattern of the teeth of 

 Oligocene horses, but it is higher than the more brachyodont forms. 

 The proportion of the height to the antero-posterior diameter is only 

 about six per cent, greater than in Mesohippus portentus from the lower 

 White River beds. 



The radius, like all the other bones of the limbs, is long and slender. 

 Its shaft is transversely concave on the posterior surface. The trans- 



