Miacis parvivortts. Cope. Gen. et sp. nov. 

 Established on a portion of the right ramus mandibuli, containing por- 

 tions of three molars, the penultimate being perfect. As in Canidce, the 

 molars diminish in size posteriorly, the last being single-rooted, the 

 penultimate being two-rooted. The structure of that tooth is approx- 

 imately that of Stypolophus, i. e., with three trihedral cusps in front and 

 a heel behind, but the cusps are of equal height, and their point of union 

 not raised above the surface of the heel . This is a valley bounded by a 

 sharp margin which is incurved to the outer cusp, leaving a vertical 

 groove on the outer side, as in Stypolophus sp. This genus further 

 differs from that one in the single-rooted small tubercular posterior molar, 

 which is wanting in that one. The ante-penultimate molar is much 

 larger than the penultimate. The crown of the latter is laterally ex- 

 panded, and bears a cingulum at the base antero-externally. Enamel 

 smooth. 



M. 



Depth ramus st penultimate molar 0.0080 



Length crown of " " .0040 



Elevation " " » 0025 



Width " " " 0033 



Found on Black's Fork of Green River. An ally of Stypolophus and 

 Triacodon. 



Tomitheritjm rostratum. Cope. Gen. et sp. nov. 

 Allied to Notharctus, Leidy. Dental formula \ \ ||, in an uninter- 

 rupted series. Last molars with five tubercles, others with four ; all 

 low and slightly alternating, the outer wearing into crescents. Canines 

 quite small. Incisors very promiuent, the median pair with transverse 

 cutting edges. Symphysis coossified, projecting in front. 



I base the distinction between this genus and Notharctus on the small 

 canine, and the sub-horizontal position of the incisors ; believing that 

 when other portions of the skeleton are studied, other differences will 

 appear. This, I have the opportunity of doing with material now in my 

 hands. 



The adjacent horns of the two outer crescents unite with the anterior 

 outer tubercle ; the posterior outer is insignificant. There is a projection 

 but no tubercle in front of the outer anterior tubercle. The first and 

 second premolars have but one root, the base of the second being about 

 the size of the base of the canine. The latter are cylindric at base. The 

 inscisors form a parabolic outline, and have entire edges, the middle pair 

 transverse ones. Enamel generally smooth, premolars somewhat striate ; 

 an indistinct inner cingulum. 



M. 



Length of entire dental series (straight) 0.044 



" symphysis mandibuli 020 



Depth ramus at second molar 010 



Length crown of " " 006 



