GEOLOGICAL SUEVEY OF THE TERRITORIES. 605 



the valley belovr. It wears into a prominent loop. The anterior cusp is 

 much less elevated than the median, and is separated from the latter by 

 a considerable ridge. The only cingulum on the molars is on the outer 

 side of the first. Enamel smooth. 



Measurements Wo. 1. 



M. 



Length of five molars , 0. 071 



Length of three posterior molars 0470 



Length of hist molar 0159 



Width of last molar 0200 



Width of penultimate molar 0210 



Length of penultimate molar 0168 



In the more perfect specimen all of the molars have two transverse 

 crests, except the P. M. 1. The lower molars possess strong anterior 

 prolongations of their posterior crests ; the third and fourth jjremolars 

 have one elevated transverse crest near their middle, and the second is 

 much compressed. The first I cannot find. Symphysis rather short 

 for the genus. 



Measurements No. 2. 



M. 



Length of sui)erior molar series 0. 085 



Length of true molars , 046 



Length of penultimate 015 



Width of penultimate 019 



Length of inferior molar series . 078 



Length of inferior true molars 047 



Length of penultimate 017 



Width of ]3enultimate ..u Oil 



Width of last xoremolar 008 



Length of last premolar „... .012 



Depth of ramus at last premolar 0235 



Length of diastema 019 



Length of bases of three incisors 018 



Hyeachyus agraeius, Leidy. 

 Common everywhere. 



Hyeachyus boops, Marsh. 



Meldletes toops, Marsh, American Journal, 1872, p. 218; Hyrachyus lodps, Cope, On 

 some Eocene Mammals, &c., 1873, p. 6. 



Bitter Creek and Black's Fork. 



Hyeachyus nanus, Marsh. 



LopModon nanus, Marsh, American Journal Sciences and Arts, 1871, July ; Hyracliyxis 

 nanus, Leidv, Geological Survey of Montana, 1871, p. 361 ; Relaletes, Marsh, 1. c, 

 1872, p. 218."^ 



Cottonwood Creek. 



ANCHIPPODCrS, Leidy. 



Proceedings Academy Natural Sciences, Philadelphia, 1868, j). 232; Trogosus, Leidy, 

 Proceedings Academy Natural Science, Philadelphia, 1871, ?aid Geological Survey of 

 Montana, 1871, p. 359. 



Anchippodus minoe, Marsh. 



Palceosyops minor. Marsh, American Journal Science and Arts, 187r, July; Trogosus 

 castoridens, Leidy, Geological Survey of Montana, 1871, p. 360. 



Cottonwood Creek. 



