June, 1912. New Titanotheres — Riggs. 33 



able to this species. These specimens are somewhat smaller and less 

 specialized than the type. They vary in length from 525 to 560 mm. 

 One of the largest, a splendidly preserved skull, is figured in Plate IX. 

 The canines as indicated by the alveoli of the type are smaller, and the 

 premaxillaries are somewhat narrower. There is little evidence of 

 incipient horn-cores. The nasals in this group of skulls overhang the 

 margin of the premaxillaries. They are laterally infolded, slightly 

 expanded in the distal third and taper to an emarginate end. They are 

 separated from the maxillary border by a wide recess. Compared with 

 D. intermedins the smaller skull (No. 12 193) approaches closely in size, 

 the dental series is similar in length, the premolars are more advanced, 

 and the cranial region is more elongate in comparison with the face. 

 However, there is a considerable variation in these proportions between 

 the several individuals referred to this species. In the palatal bones 

 of these specimens there is an offset between the last molars correspond- 

 ing to the position of the nareal margin in other closely related titano- 

 theres. This is evidently a vestige, marking the former position of the 

 narial opening. It has been bridged over by the outgrowth of thinner 

 plates from the lateral margin of the palatal bones so that the nares have 

 receded to appoint behind the hamular processes of the pterygoids. The 

 plates of this secondary palate are so thin that they are often broken 

 through and so the vestigial offset may be mistaken for the narial 

 margin. The secondary palate in this species is pierced by a pair of 

 foramina; its posterior extension is an enfoliate process free from the 

 lateral walls and probably attached to the inferior margins of the vomer. 

 A mandible associated with an incomplete skull (No. 12200) is 

 relatively strong, curved in the ramus and broad at the angle. (PI. IX, 

 Fig. 2.) There is also a large part of a skeleton associated with this 

 specimen which is not yet prepared for study. A detailed description 

 of this entire specimen will be given in a later publication. 



D. flutninalis sp. nov. 



Type specimen, No. 12205 Field Museum. (PI. X, Figs. 1-3). 



Type locality: Amynodon Sandstone, Uintah B. 



Specific characters: Skull, small and narrow (520x230 mm.), facial 

 region much shorter than cranial, nasals narrow and slightly 

 tapering, posterior nares opening between hamular processes, 

 post-orbital process of jugal back of the last molar, molar-pre- 

 molar series 171 mm.; canines short and recurved, incipient 

 horn-cores in the form of high narrow ridges. 



This species is represented by a single splendidly preserved skull 

 with almost complete dentition, collected by M. G. Mehl. The skull 



