This name is pre-occupied ; see TMnoiherium annulatum, Cope (Pro- 

 ceed. Am. Philos. Soc. 1870-1). 



Locality. — Found by myself in the Bathmodon bone bed, near Evans- 

 ton, Wyoming. 



OltOTHERITJM INDEX. Sp. nOV. 



Represented by both mandibular ramus with many of the molars in 

 good preservation. These number P. M. 3, M. 3. The last premolar is 

 somewhat like the first molar, but has but one posterior tubercle, and 

 adds a cingular projection in front of the anterior pair. The first pre- 

 molar has two roots ; the second is compressed, and with a broad heel 

 behind. In the molars the anterior tubercles are connected by a cross 

 ridge ; the posterior are a little more distinct from each other. The inner 

 anterior tubercle is obtuse but not bifid, and its base is connected with 

 the apex of the posterior outer by a diagonal ridge. There is a small 

 median posterior tubercle on the No. 2, and a large heel on the last molar. 

 It supports a conic tubercle, which is connected by sharp ridges with the 

 tubercles preceding it. There is a cingulum on the outer face of the 

 true molars, which does not extend on the base of the tubercle of the 

 posterior pair. 



Measurements. M. 



Length of molar series 0.0350 



" " first premolar 0032 



" "third " 0055 



Width " " " 0040 



Length " second molar 0065 



Width " " " 0045 



Length " last " 0098 



Depth of ramus at first premolar. . 0021 



" " " second molar .0023 



Note. In determining the vertebrata of the Bridger Eocene, I have 

 had recourse to the papers published by Prof. Marsh on this subject. It 

 is well known his descriptions are short, yet, for the species, they are 

 frequently sufficient. The case is otherwise with the genera, of which at 

 least forty are named, very few of which are defined or characterized. 

 In thirty, no mention is made of the numbers of either the premolar or 

 molar teeth. In these manifold omissions we may discover not only 

 the wisdom of silence, but also the silence of wisdom. It is to be hoped 

 that Prof. Marsh will soon place his important results within reach of 

 students, and allow his names to take a place in nomenclature, by an 

 early publication of explanatory diagnoses. 



October 25th, 1873. 



r 



