GEOLOGICAL SURVEY OF THE TEREITORIES. 565 



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

 don 4: — 2, but jnclgins from the forms of the crowns, it should be 1 — 5. 

 However this should be, I liave no doubt that as in other Proboscidia the 

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

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

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

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

 anterior two form a chevron with open apex 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 

 curved upwards so as to resemble slightly the narrow i)row 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 forwards, and the anterior pair issue from the jaw in contact. 

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

 is facilitated by the presence of the mental foramen below the jjosterior 

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

 all Jlammalia, 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 upj)er jaw, and is rendered i)robable by 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 Bathmodon and Palceosyops the 

 canines are thrown into the incisor series as in Ruminantia, and in PaJ(B- 

 osyops the outer incisors are much reduced. In sev^eral genera there are 

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

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

 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 PaUt'osyops and 

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

 lerior 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 opi)ose the canines of the 

 upper jaw. 



LOXOLOPHODON, Cope. 



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

 August 19; and p. 488, (August 22.) Tiuoceras, 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-shaped, but is anteriorly concave, and tiatteued 

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

 This extremity 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 temporal 

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

 level of the middle of the x^arietal bones. This portion of the skull is 

 injured in my only specimen. The occipital rises in a wall upward from 

 the foramen magnum^ and supports, probably, a little in front of the junc- 

 tion with the superior and inferior ridges bounding the temporal fossa, a 

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

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



