368 R. L. Troxell — Entelodonts in Marsh Collection. 



neath the orbit and the great breadth make it like A. 

 marshi (fig. 10) . The posterior process of the jugal bends 

 down sharply at its tip and becomes flat and broad where 

 it rests in the corner notched ont of the border of the 

 glenoid cavity. This seems to be a uniqne f eatnre in the 

 species, although skulls referred to A. mortoni are re- 

 ported to have it. 



Fig. 5. — Archceotlierium clavus darbyi, subsp. nov. Holotype. Cat. No. 

 10032. Back view of skull. One-fifth nat. size. 



The outer end of the temporal forms a heavy broad 

 edge with a peculiar fossa near the summit of the tubercle 

 (see fig. 5), the nature of which is unknown. Where the 

 upper border of this bone curves forward into the an- 

 terior process, it is about 35 mm. from the condylar sur- 

 face. The anterior process of the temporal curves 

 upward and inward to join the jugal, and is similar, in its 

 greater width vertical, its sigmoid curve ventral, and its 

 general massiveness, to that of A. marshi. It is very dif- 

 ferent in this respect from the type of A. clavus clavus 



(fig. i). 



The supra-occipital is very well preserved and shows a 

 far overhanging crest. The crest divides and sends out 

 two wings posteriorly, but even before it divides, it covers 

 a deep depression on the under side in which are two dis- 

 tinct pits. Flying buttresses, as it were, extend outward 

 and forward, joining with the temporal and exoccipital 

 bones above the external auditory meatus. Immediately 

 above the condyles, a marked fossa may be seen, but the 

 foramen shown in some species appears only on one side. 

 The posterior border of the infra-orbital foramen is over 

 the anterior edge of P 3 ; it is rounded and not flat or oval 

 as in other specimens. 



The foramen ovale leading through the temporal and 

 opening forward is plainly shown near the suture of the 



