128 F. B. Loomis — Wasatch and Wind River Rodents. 



Par amy s bicuspis sp. nov. 



Type No. 451, an upper jaw of the left side and a lower 

 jaw from the right side, each with three teeth, and found in 

 the Wind River beds on Bridger Creek near Lost Cabin, Wyo. 



In size the species is about the same as P. copei, but is 

 clearly distinguished by the mesostyle being double. On the 

 fourth premolar and the first two molars of the upper jaw 

 there is a strong anterior and a posterior marginal ridge. The 

 protocone is well developed, the hypocone merely indicated. 

 From the paracone a ridge (low in the middle) runs to the 

 protocone, yoking them. From the metacone also a ridge runs 

 inward to the metaconule. On premolar 4 and molar 1 the 

 ridge appears a series of tiny cusps, but on molar 2 the ridge 

 is less complete and the metaconule is distinct. The lower 

 molars have low marginal cusps, the paraconid being very 

 prominent. While shallow the interior basin is large. There 

 is a posterior marginal ridge, and in front an anterior marginal 

 ridge, incomplete in the middle. Then on the slopes of the 

 protoconid and paraconid, facing each other, there is a trace of 

 a fold. The posterior ridge of the last molar is a broad 

 inrolled buttress very characteristic of the species. A broken 

 face of the incisor is 4| mm deep by 2J mm wide. The four 

 molariform lower teeth measure 14 mm . 



Paramys copei sp. nov. 



Type No. 4755 of the Cope collection in the Amer. Museum 

 of Natural History, already figured and described by Cope as 

 Plesiarctomys delicatissimus Leicly.* The custom of assigning 

 Wind River specimens to Bridger species was here followed 

 by Cope. 



This species is a trifle larger than P. delicatissimus. Lower 

 premolar 4 of P. copei has a larger and smaller cusp ante- 

 riorly; while P. delicatissimus has but a single cusp in the 

 same position. The cusps of P. copei are less plump and the 

 interior basin is larger. The upper molars can not be com- 

 pared, as P. delicatissimus is founded on a lower jaw and is a 

 rare species. The upper teeth of P. copei are marked by the 

 ridges from the paracone and metacone being simple and 

 including the paraconule and metaconule respectively. The 

 mesostyle is simple. The known specimens are found in the 

 Wind River beds along the Wind River in Wyoming. 



Paramys major sp. nov. 



Type No. 327a, a lower jaw found in the Wind River beds 

 on Bridger Creek near Lost Cabin, Wyo. ; and the same form 



*Rep. U. S. Geol. Surv. Terri., vol. iii, p. 182 ; and pi. 24a, fig. 1-10. 



