E. L. Troxell — Entelodonts in Marsh Collection. 381 



cess in A. eras sum, on its anterior general border, is in 

 line with the posterior border of the orbit ; in the specimen 

 now being described it is some 30 mm. further back. The 

 process itself is symmetrical on its anterior and posterior 

 sides, while the type of A. eras sum has a flange anteriorly 

 not duplicated behind. The lower end is very much thick- 

 ened, is -broad, and is roughened for muscle attachment. 

 The posterior process from the malar does not fit into 

 any notch on the glenoid lip nor above it. The post-or- 

 bital branch of the malar is heavy but has a marked fossa 



Fig. 10. — Archceotherium marslii, sp. nov. Holotype. Cat. No. 12025. 

 Side view of skull and jaws. Compare PI. I, A, as apotype of A. crassum. 

 One-fif tli nat. size. 



on its outer surface ; none is to be found in the holotype of 

 A. clavus clavus nor of A. crassum; rather, in the latter 

 the cross-section is almost oval. On the process which ex- 

 tends forward from the temporal (and measured from the 

 condyle), the vertical diameter is very great, over 58 mm. 

 This process has a strong sigmoid curve on its ventral 

 border; it is very wide in contrast to that of A. crassum, 

 which has no such curve. The glenoid cavity is not cut 

 away on its border to receive the end of the malar pro- 

 cess, nor is it notched above the fossa as in A. clavus 

 clavus. 



Am. Jour. Sci. 

 28 



Fourth Series, Vol. L, No. 299. — November, 1920. 



