PALiEOSYOPS. 701 



rapidly in size posteriorly. In the last molar the ridge connecting the 

 posterior lobe with the median is low, only giving a connecting dentinal 

 band after considerable wear. The inferior canine is not very robust. 



Measurements. 



M. 



Length of complete ramus from anterior base of Pm. iv 0.295 



Length of do. posterior to M. iii 143 



Depth of ramus at Pm. ii 051 



Depth of ramus at M. iii anteriorly 07'2 



Diameter of inferior canine at base of crown 018 



I found the specimens above described in the Mammoth Buttes, South- 

 western Wyoming, near the headwaters of Bitter Creek. The formation 

 is the Washakie basin of the Bridger. Since my examination of this locality 

 the Princeton Exploring party obtained specimens of this species in the 

 same region. 



PALiEOSYOPS MAJOR Lcidy. 



Survey of Wyoming, 1871, p. 359. Report U. S. Geol. .Survey Terrs., 1873, 1, p. 45. Report of the Prince- 

 ton Scientitic Expedition, 1878, p. 27. Limnohyus robustus, Marsh, Anier. Jour. Science and Arts, 

 1872, p. 124. 



Plate LI, fig. 2; LII, figs. 1, 2. 



I found remains of this species not uncommon in the Bridger region^ 

 especially on Cottonwood Creek, Black's Fork of Green River, etc. I can- 

 not add anything to the descriptions above cited. 



Pal.s;osyops L.a;viDENS Cope. 



Annual Report U. S. Geol. Surv. Terrs., 1872 (1873), p. 591, and Report U. S. Geol. Snrv. Terrs., I, 1873, 

 p. 30; not loc. cit., j). 28, nor Limnohyvs Iceeidens, Cope; Proceed. Amer. Philos. Soc, 1873, pub- 

 lished January 31. Falwosyops paludosus, Leidy; Hayden's Survey of Montana, 1871, p. 359; 

 Proceed. Acad. Nat. Sci., Philada., 1870, p. 113. 



Plate L, figs. 1-3. 



This species is smaller than the P. major, but Dr. Leidy was not satisfied 

 that it is entitled to distinct specific rank on this account. In my report 

 to Dr. Hayden in 1872, I distinguished it from the P. major by the simply 

 lobate form of the external wall of the second superior premolar. In P. 

 major this tooth has two external lobes as in the succeeding premolars, the 

 posterior lobe being smaller than the anterior. This character of the P. 

 IcBvidens is displayed in Dr. Leidy's figures. 



