GEOLOGICAL SURVEY OF THE TERRITORIES. 565 



relative sizes of the teeth, I have written the molar series of Loxolopho- 

 don 4 — 2, but jiulgiiii!: from the forms of the crowns, it shouUl be 1 — 5. 

 However this shouUl be, I have no donbt that as in other Frohoscidia tlio 

 premolar and not the molar series is deticient, and that there are three 

 or four true molars at least. In a mandible fonnd alone, which agrees in 

 size with some species of Uintathcrmm^ six molars are preserved. Of 

 these the posterior two display' three snb-transverse crests, of which the 

 anterior two form a chevron with open iipex directed to the inside. An- 

 terior to the front crest is a cingnlar tubercle. The symphyseal part of 

 the jaw is remarkable: it is co-ossified, exceedingly compressed, and 

 carved upwards so as to resemble slightly the narrow prow of a South 

 Sea boat. There are two teeth on each side, which are separated from 

 the molars by a diastema. They are much compressed and curved up- 

 wards and forwaids, and the anterior pair issue from the jaw in contact. 

 The crowns are lost in the specimen. The determination of these teeth 

 is f:icilit;ited by the presence of the ment-al foramen below the posterior 

 one. This foramen issues, as is well known, posterior to the canines in 

 all Jllammalid, and either below premolars or the diastema. The two 

 teeth in our fossil will then be premolar and canine respectively, and the 

 incisors must be regarded as wanting. This is in conformity with the 

 structure of the upper jaw, and is rendered probable bj^ the great reduc- 

 tion of the symphysis of the lower jaw in the species. It is also suggested 

 by the almost universal tendency to reduction of the incisors seen in the 

 mammals of the same extinct fauna. In B<tthmodon awl Falcwsyops the 

 canines are thrown into the incisor series as in Rmniimntia, and in Pake- 

 osyops the outer incisors are much reduced. In several genera there are 

 but two incisors. Finally, in ^ynoplotlierium the large inferior teeth de- 

 scribed by myself as incisors, and which resemble the cutters of Rodentia^ 

 are immediately in front of the mental foramen, and bear the same rela- 

 tion to it and to the premolar teeth, as do the canines of Pahcosyops and 

 other Mammalia. Hence I believe these to be canines, and that the in- 

 ferior incisors are wanting in my specimen. The probability of the 

 truth of this determination is increased by the presence of a small inter- 

 val between them, and by the fact that they opjjose the canines of the 

 upper jaw. 



LOXOLOPHODON, Cope. 



Proceedings American Philosopliical Society, 1872, p. 580, extra copies published 

 August 19; and p. 488, (August 22.) Tinoceras, Marsh, American Journal of Sci- 

 ence and Arts, 1872, (October.) Published (described) September 21. 



The cranium in this genus is very elongated and compressed. The 

 muzzle is posteriorly roof-slmped, but is anteriorly concave, and flattened 

 out into a bilobed shovel, which rises above the extremity of the bone. 

 This extremitj' is subconic, and short and decurved. A second pair of 

 horn-cores stands above the orbits ; each one composed externally of the 

 maxillary bone, and internally of an upward extension of the posterior 

 part of the nasal. Behind this horn the superior margin of the tenjpo) al 

 fossa sinks, but rises again at its posterior portion, probably above the 

 level of the middle of tlie parietal bones. This portion of the skull is 

 injured in my only specimen. The occi].»ital rises in a wall upward from 

 the foramen maynum, and supports, i)robably, a little in front of the junc- 

 tion with the superior and inferior ridges bounding the temporal foss-.i, a 

 third horn-core on each side. The base of this core is as stout as tliat 

 above the orbit, and subcyliudric in section. The temporal fossa has its 



