E. L. Troxell — Entelodonts in Marsh Collection. 365 



straight out from the maxillary ; the inner cone, the deu- 

 tercone, points slightly forward (the cusps are indicated 

 on figs. 17, 18). The general form is quadrate or trap- 

 ezoidal, with a notch or angle in the antero-internal cor- 

 ner. The inner border is more straight than rounded as 

 in other species. The dimensions, longitudinal and trans- 

 verse, are equal. Cingula are present, both front and 

 rear, and are especially developed before and behind the 

 deuterocone. 



The first upper molar, as in most specimens, is much 

 worn, although the individual would not be judged as very 

 old. The outline is almost square as contrasted with 

 those species in which M 1 is rounded or more irregular, 

 and in contrast with M 2 in the same specimen, which is 

 much wider anteriorly. In the manner of wear, this tooth 

 is deeply hollowed out and is sheared off on one inner cor- 

 ner. 



M 2 has straight edges and sharp corners to an unusual 

 degree, but it is very much narrower behind than across 

 the proto- and paracones. It is for this reason even 

 broader than it is long, and the base of the paracone is 

 very heavy. It is considerably larger than M 1 and very 

 much larger than M 3 . By the lakes remaining, it can be 

 seen that the hypoconule and protoconule are well formed 

 and there are well developed cingula, both anterior and 

 posterior. 



M 3 is almost triangular and shows distinctly a diminu- 

 tion in the tooth series by this terminal member. In its 

 greater width anteriorly it resembles slightly the tooth in 

 front, but the back and inner sides form an almost contin- 

 uous curve. The outer and front sides are quite straight, 

 and the base of the paracone stands prominently between 

 them. The protocone has a position midway fore and aft, 

 and has encroached on the hypocone so that the latter is 

 scarcely visible ; it is, in fact, smaller than the metaconule 

 and is nothing more than a heel, continuous with the hypo- 

 style. The metacone is also lower than the metaconule, 

 which already shows a lake of dentine by reason of the 

 wear. There is a very strong cingular shelf anterior. 



The diastemata separating the teeth of this species 

 show some interesting features: Between I 2 - 3 , 6 mm.; 

 T-C 1 , 12.6 mm. ; CVP 1 , 2 mm. ; P 1 - 2 , 14.3 mm. ; P 2 - 3 , 5.5 mm. ; 

 P 3 - 4 , zero. 



Am. Jour. Sci. — Fourth Series, Vol. L. No. 299. — November, 1920. 



27 



