608 • GEOLOGICAL SURVEY OF THE TERRITORIES. 



teeth present four cusps, of which the outer are crescentoid in section, 

 the inner conic. They are all elevated, and the inner anterior is in both 

 teeth compressed and bifid. It receives an oblique ridge from the outer 

 posterior crescent, which also sends a ridge to the posterior inner. 

 Enamel smooth. 



Mcasurcmcjits. 



M, 



Leuojth of penultimate molar 0. 0045 



Width of penultimate molar behind 0040 



DeiJth of ramus at posterior margin of penultimate molar 0070 



This is a small mammal, about equal in size to a weasel. 

 Antiacodon fukcatus, Cope. 



On some Eocene Mammals, &c., p. 1, March 8, 1873. 



Established on a part of the right ramus mandibuli, with the three 

 molars and last premolar in perfect preservation. Tbe crowns of the 

 molars are composed of two external, chevron-shaped tubercles, the apices 

 rising as acute cusps, and two internal cones, the interior of which is 

 flattened and strongly bifid, both points being more elevated than any 

 of the others. The cusps are nearly opposite to each other, and be- 

 hind the interval between the two posterior rises another, not so ele- 

 vated as the others, except on the posterior molar. Here it is elevated, 

 and nearly equidistant from the two in front of it. The enamel is 

 smooth, and there is no cingulum on either side. The premolar consists 

 of a principal sectorial cusp, and has a smaller but stout acute anterior 

 cusp, with a small rudiment of another behind ; a stout cusp rises from 

 the inner i)Osterior margin of the principal one, giving it a subbifid 

 appearance. 



Measiircments. 



M. 



Length of four molars 0. 0195 



Length of three true molars 0149 



Length of last true molar 0055 



Length of first true molar 0043 



Width of first true molar front 0025 



Width of first true molar ])osteriorly 0031 



Depth of ranius at front of M. 3 0075 



Depth of ramus at front of P. M. last 0055 



This species differs from the last in the presence of the posterior 

 tubercles on the M. 2-3, and the absence of external cingulum. The 

 sizes are not very different. 



Eroni the bluffs of the Upper Green River. 



The genus to which this species belongs differs from Eyopsodvsin the 

 carnivorous form of the last premolar, which has a well-developed an- 

 terior cusp. I refer it to the same genus as the last species, though its 

 characters have never been pointed out by the author of the name, (Pro- 

 fessor Marsh,) nor are the characters which distinguish it from Eoma- 

 codon of the same author discoverable. He states that the cusps in H- 

 vagans are " isolated," a character which does not apply to A. fuxcutiis, 

 in which they are related much as in nyoi)sodus. 



