132 Annals of the Carnegie Museum, 



terior and posterior external cones, and stands at the apex of a tri- 

 angle, the base of which would be formed by a line connecting the 

 two latter cones. A rather strong basal cingulum extends all along 

 the external and anterointernal borders of this tooth, completely sur- 

 rounding externally the anteroexternal cone. There is no basal cin- 

 gulum on the posterointernal border of this tooth. 



Premolari is a much smaller and simpler tooth than P.^ or M.i 

 which immediately precede and succeed it. The crown of P.-^- sup- 

 ports but two cones, the one external, the other internal. The former 

 is a little the more prominent of the two. This tooth is quadrangular 

 in outline and bears a basal cingulum on its exterior, anterior, and 

 posterior borders, but not on its interior border. 



Commencing with M.i the molars gradually decrease in size and be- 

 come less complicated from M.i to M.^. The crown of M.J- is subquad- 

 rangular in outline, and bears three principal cones, two of which are 

 external and of about equal size, while the third is internal and some- 

 what larger. This internal cone shows a decided tendency to divide 

 into anterior and posterior internal cones, the latter of which is much 

 the smaller of the two and partakes more of the nature of a conule. 

 Two ridges diverge from near the apex of the internal cone of this tooth 

 and form small anterior and posterior intermediate cones, or conules, 

 so that there are on MJ six cusps, two of which are external, two in- 

 ternal, and two intermediate. The two intermediate and the postero- 

 internal are much less prominent than the other three. A basal cin- 

 gulum surrounds the external and anterior and posterior borders of 

 this tooth. 



The succeeding tooth, M.-3-, has a quadrangular crown, supporting 

 two external cones and a somewhat larger internal cone, which shows 

 less tendency to division than does the same cone on M.i, but does, 

 nevertheless, show a small conule developing near the apex on its pos- 

 terior side. The two intermediate cones mentioned as present on the 

 crown of M.i- are also present on M.^-. There is a basal cingulum on 

 the external and posterior and anterior borders of this tooth. 



Molar^- is much the smaller tooth of the molar series, and is of some- 

 what simpler structure than the others. There are two small external 

 cones and a rather prominent, perfectly simple, inner cusp, with but 

 faint indications of the intermediate conules noticed in M.-^ and M.^. 

 A basal cingulum surrounds the tooth except on the internal side, 

 where it is cpiite smooth. 



