E. L. Troxell — Entelodonts in Marsh Collection. 379 



Following are the characters of this species as taken 

 from the holotype of A. eras sum: Narrow but thick 

 dependent process with a width about one fourth the 

 length and having a sigmoid curve; the tip is turned 

 backward in a rounded lobe; a thin edge extends for- 

 ward; the process hangs from not far back of the rear 

 line of the orbit, and all its parts are rounded or oval 

 and not flat; slender processes form the suture between 

 the jugal and the temporal, and that from the jugal 

 does not reach the glenoid cavity, cf. A. clavus; this cav- 

 ity, the edges of which are not sharp, is wide rather than 

 long and is rounded and more nearly symmetrical than 

 they are ordinarily. 



Added to the features enumerated for the holotype are 

 these characters from the associated specimens of the 

 group : large mental processes situated well forward of 

 the bifurcation, the posterior side of these longest, i. e., 

 recurved; flat chin anteriorly; body of symphysis heavy 

 and long ; premolar teeth large, double-rooted, with small 

 diastema. (Specimen No. 10036 is about one fifth smaller 

 than specimen No. 10037.) 



Akch^otheeium marshi G-roup. 

 Archce other ium marshi, sp. no v. 



Holotype, Cat. No. 12025, Y. P. M. Lower Oligocene. Cheyenne River 

 near French Creek, South Dakota. 



The original description of this specimen (figs. 10-12) 

 was made by Professor Marsh (1893, pp. 408-409), in 

 amplification of his species A. crassum, and speaking of 

 the entelodont material which had been gathered together. 

 He says in part : 



' ' Explorations begun by the writer in 1874, in Nebraska and 

 Dakota, resulted in finding several additional specimens, and 

 others have since been obtained in the same region during the 

 explorations made for the U. S. Geological Survey. Still other 

 very perfect specimens have been secured by the Yale Museum, 

 so that now ample material is available for investigating both the 

 present species and its near allies. 



/'On Plate VIII of this article [PL I, A] is represented, one- 

 eighth natural size, a skull of Elotherium crassum, which is one 

 of the most perfect ever discovered. The lower jaws are in place, 

 and the nearly complete dentition is present and in fine condi- 

 tion. Figure 1 shows this skull as seen from the left side, with 

 the jaws shut closely together, as found. One of the most notice- 



