422 F. B. Loomis — Hyopsodidce. 



small cusp. The protolophid and metalopliid are both well 

 developed on the first and second molars but on molar three 

 the latter is very weak. The hypoconnlid is small on the first 

 two molars but developed into a prominent heel on the last, 

 the entoconid being tiny. The upper molars are those typical 

 of the genus, having a cingnlum in front, outside and behind. 



The specimens run uniform in size, 

 the three inferior molars measuring 

 12 mm . On Bridger Cr., 37 speci- 

 mens were collected and the species 



Fig. 5. Hiiopsodus wort- -, . ,-, ,-, -r Tr . -, V>« 



mani. x '*. occurs also in the other Wind Kiver 



localities. 



Hyopsodus minor sp. no v. 

 Though but one example of this tiny form was found, it 

 differs so materially from H. wortmani that it is impossible to 

 include it in that species. The type specimen is part of the 

 right ramus with the three molars measuring together 10 mm . , 



The teeth are short, with obtuse but well-separated cusps, 

 and have a cingnlum in front and a trace of it between the 

 external cusps. The proto- and meta-conids are set close 

 together and united by both a protolophid 

 and metalopliid. The hypoconid has a 

 strong ridge running to the metaconid, while 

 the hypoconulid and entoconid are both 



b ig. b. Hyopsodus . it t i 



minor, x f . strongly developed. 



The species is distinguished by its small 

 size, presence of a cingulum externally and the strength of the 

 ento- and hypoconulid. The locality is Bridger Cr., Wyoming, 

 in the Wind Kiver horizon. 



Hyopsodus browni sp. nov. 



This, the most abundant species in the Wind River beds, is 

 named in recognition of the successful work of Mr. T. C. 

 Brown in collecting these forms. The type is a left ramus 

 with the molars and fourth premolar ; while an upper jaw 

 with premolars three and four is associated with it as co-type. 

 A less complete specimen has both upper and lower dentition. 



The teeth of the lower jaw are short and stout with obtuse 

 cusps, and a cingulum along the front only. On the fourth 

 premolar the deuteroconid is merely indicated by a small cusp, 

 and behind on the proterior margin of the basin, there is a 

 small external cusp. On all the molars the proto- and meta- 

 conids are set close together and united by both a proto- and 

 meta-lophid. The hypoconid is large and connected the meta- 

 conid by a wide ridge. The hypoconulid is rather large on all 

 the molars but does not make a strong heel on the third molar. 



The upper molars have a cingulum in front, outside and 

 behind ; on the which, where it meets the ridge from the para- 



