0. C. Marsh — Eastern Miohippus Beds. 



93 



Heptacodon arm at us, sp. no v. 



Figure 2, below, represents natural size the last right upper 

 molar of another large ungulate mammal, the exact affinities 

 of which cannot now be determined. This tooth is considera- 

 bly worn, showing that it belonged to an old animal. The 

 remaining molars and part of the premolars in the same series 

 are preserved, and with them a very large canine still in posi- 

 tion in the jaw. All are worn, but otherwise in good preserva- 

 tion. The tooth figured has a crown composed of live main 

 cusps, the antero- median being the smallest. The outer but- 

 tresses are of moderate size, and there is none at the posterior 

 angle. The enamel of this tooth and of all the series is rugose. 

 The true molars differ greatly in size, the first being quite 

 small, the second intermediate, and the last equal in bulk to 

 the two others. 



The last premolar has one outer and one inner cusp. The 

 next tooth in front is larger, and has a triangular crown, and 

 the next is close to it. The canine is very large, dependent, 

 and oval in section. Behind it is a long diastema. 



4flfc 



Figure 1. — Last upper molar of Octacodon valens, Marsh ; seen from below. 

 Figure 2. — The same tooth of Heptacodon armatus, Marsh; seen from below. 

 Both figures are natural size. 



Protoceras comptus, sp. now 



A second species of this interesting genus is indicated by a 

 young skull from the same horizon in which the type was 

 found. This specimen, apparently the skull of a female, is in 

 good preservation, and, when compared with the type, differs 

 in several essential points. The maxillary plates are not ele- 

 vated along the sides of the nasal aperture, and the posterior 

 nares extend forward to between the first true molars. The 

 whole skull is proportionally more elongate, and the facial part 

 especially jDroduced. 



