Pantolestes longietjndus. Cope. 

 Gen. et sp. nov. 

 This form is one of those mixed types which are so abundant in the 

 Bridger Group. Its dental formula is M. 3, P. M. 3 ; c. 1. incisors un- 

 known. The molars in the only specimen known are worn as to pre- 

 clude exact description. They evidently possessed anterior and posterior 

 lobes, separated by a valley, which was most expanded on the inner side. 

 The last molar exhibits a projecting keel posteriorly, which probably 

 supported a small tubercle. The three premolars are all two-rooted and 

 compressed in form. The last presents a crown composed of one large 

 anterior compressed cusp, and a much lower posterior one. There is a 

 slight cingulum in front. The canine is lost, but its alveolus indicates 

 that it was a stout tooth. 



So far as the known dental structure goes, this genus resembles nearly 

 the Notliarctus of Leidy (Limnotherium of Marsh), but possesses one 

 premolar tooth less. 



The mandibular ramus is quite slender, and there is a large foramen 

 below the first true molar. The masseteric fossa is pronounced. 



M. 



Length of dental series to canine 0.0280 



" " three molars ,0140 



" " second " -0041 



Width " " " 0030 



There- were found associated with this jaw some caudal vertebrae of 

 very attenuated form, which point to the possession of a long tail by this 

 animal. One of these displays six short processes arranged round the 

 articular extremity, the neural arch not being completed. 



M. 



Length 0.016 



Proximal diameter 003 



Median " .-., 0018 



PSEUDOTOMUS HIANS. Cope. 



Gen. et sp. nov. 

 This form is interesting as the only member of the Edentate order yet 

 discovered in our early Tertiary formations. It is represented by a 

 species of which a nearly perfect cranium is in my possession. This is 

 about the size of an agonti and is of a depressed form. It has a thin 

 molar and zygomatic arch, but no postorbital. There is a large suborbital 

 foramen. The dentition consists of two pairs of long curved teeth, hav- 

 ing much the form- w and position of the cutting teeth of Bodentia. These 

 are placed widely apart in the upper jaw, allowing space for the greater 

 portion of the premaxillary between them . The mandibular cutters are 

 less widely separated by a narrow prolongation of the symphysis. The 

 exposure of the tooth is lateral, its direction nearly anterior. It projects 

 anteriorly very little beyond the symphysis, and has a horizontal triturat- 

 ing surface below the level of the latter. Neither pair of cutting teeth 



