608 GEOLOGICAL SUEVEY OF THE TEREITOEIES. 



teeth present four cusps, of whicli 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. 



Measurements. 



Length of penultimate molar 0. 0045 



Width, of penultimate molar behind , 0040 



Depth of ramus at posterior margin of penultimate molar 0070 



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

 Antiacodon fueoatus. Cope. 



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



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

 molars and last premolar in perfect preservation. The 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 ciugulum on either side. The premolar consists 

 of a principal sectorial cus}), and has a smaller but stout acute anterior 

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

 the inner posterior margin of the principal one, giving it a subbifid 

 appearance. 



Measurements. 



* 



Length of four molars 0, 



Length of three true molars 



Length of last true molar 



Length of first true molar 



Width of first true molar front 



Width of first true molar posteriorly 



Depth of ramus at front of M. 3 



Depth of ramus at front of P. M. last 



M. 

 0195 

 0149 

 0055 

 0043 

 0025 

 0031 

 0075 

 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. 



From the bluffs of the Upper Green Eiver. 



The genus to which this species belongs differs from HyoTpsodus m-ilnQ 

 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 Homa- 

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

 "nagans are " isolated," a character which does not apply to A. furcutus, 

 m which they are related much as in Hyopsodus. 



