H 



Diameters M. i < ' 



< trausverso... 



342 THE BKIDGER FAUNA. 



Tlie cusps on the true molars are, as in the M.ferox, small, and not large 

 and closely placed as in M. protogonioides. The intermediate ones are 

 nearly obsolete. The crowns are all entirely surrounded by a cingnlum. The 

 entire enamel surfaces wrinkled so as to be rugose, although the teeth are 

 those of an adult and well used. The second superior molar is larger than 

 the first, exceeding it in the transverse rather than tlie fore-and-aft diameter. 

 The third is the smallest, and is of oval form with obliquely truncate external 

 face. It is less reduced than in the M. turgidus. 



The fourth premolar consi.sts of a strong compressed-conic cusp with 

 three basal cusps of small size, viz., an anterior, a posterior, and an internal. 

 The last is the larger, though small ; is formed like a heel, and is connected 

 with the others by a cingulum. No external cingulum. 



MeaMirementn. 



M. 

 Length of last lour molars 036 



Diamete™P-m.iv^''"''>^"P°«'"''"" "1" 



transveiM! 008 



rior 010 



-• 010 



■^, . ,, ... (anteroposterior 008 



Diameters M. iii { ^ 



( trausverse Oil 



From the Upper Puerco beds; D. Baldwin. 



ACHiENODON Cope. 



Paleontological Bulletin, No. 17, \>. 2, Oct. 25, 1873. U. S. Gcol. Surv. Terrs. Auu. Rep. for 1873, p. 457. 



Known from the skull only. Dentition: I. ; C. -; Pm. .; M. - 



^ ;',' i' 4 3 



Canines well developed ; dental series without diastema First superior 

 premolar two-rooted ; crown of second (third) compressed, simple. Crown 

 of third (fourth) with one external and one internal principal tubercles. Su- 

 perior molars quadritubercular. First inferior premolar one-rooted. Crowns 

 of third and fourth compressed, simple. First and second true molars 

 quadritubercular; of third true molar with five lobes, the posterior one 

 forming a heel. Symphysis not coiissified. 



This genus agrees witli other AniocyonidoB in the presence of a preglenoid 

 crest. Its relationships to the other genera of the family appear to be quite 

 clo.se It is not yet absolutely certain whether there are four or three in- 

 ferior j>rem<)lars. In case the latter is the correct number, the first pre- 

 molar is two-rooted. 



