482 SINCLAIR— ENTELODONTS FROM THE 



were made in digging up roots. The root, held firmly in the ground 

 at both ends and looped over the teeth which pulled until it broke, 

 and being covered with abrasive grit, would wear just such marks 

 as the teeth actually display." I have modified the drawing of the 

 worn area at the base of the upper canine and redrawn the lower 

 incisors, of which but one, the left if, remains, a small tooth sloping 

 forward, the point flanked on either side by subsidiary, mammillated 

 cuspules. Broken stumps of the first right and third left incisors 

 remain and these are worn down flush with the gum by the same 

 root-digging which grooved the other teeth. I have endeavored to 

 suggest this habit in the generic name proposed. 



Striking differences in both dental and cranial characters sep- 

 arate Scaptohyus from the other large entelodonts of the Protoceras 

 beds, with which it can not possibly be confused if adequate material 

 for comparative purposes is available. The large upper incisors 

 point vertically downward, unlike the Princeton specimen of Mega- 

 chcerus, and, in shape, are hemi-cones, flattened internally, the third 

 grooved on the outer side in the manner already described. A sim- 

 ilar broad groove is found on the posterior inner surface of the 

 upper canine at the base of the enamel. 



Pi is small, but double-rooted, measuring 34 mm. anteroposte- 

 riorly on the alveolar border by 16 transversely, and separated from 

 the canine in front by a 19 mm. interval and frorri p2 by a space 

 47-52 mm. long. The crown is convex on both sides, with finely 

 rugose enamel, is thicker in front than behind, with acute edges 

 front and rear, and curves slightly backward. There is a very 

 slight cingulum both antero- and postero-internally. 



P2 is stouter and also double-rooted, 37 mm. anteroposteriorly 

 on the alveolar border by 21 transversely, is convex on both sides, 

 curves inward, with weak cingulum front and rear and a sharp 

 cutting edge behind, but extending only half way down the crown in 

 front. Enamel faintly rugose. Diastema of 32-43 mm. between 

 this tooth and the next in series. 



P3 is a large simple cone without heel, 46^ mm. anteroposte- 

 riorly by 30 transversely. The crown has a moderate cingulum in- 

 ternally, broad cutting edge posteriorly and many vertical ridges and 



