E. L. Troxell — Entelodonts in Marsh Collection. 369 



tympanic. Around the tympanic bullae, which are only 

 slightly convex, are grouped several foramina, chief 

 among which is the rounded lacerum posterius, situated 

 at the postero-internal angle of the bulla, and immediately 

 back of it and almost adjoining it, the hypoglossal fora- 

 men. "What appears to be the eustachian foramen lies on 

 the anterior end of the tympanic bulla ; the foramen or- 

 bitale and the optic foramen open into the point of the 

 V-shaped groove within the orbit; the anterior palatine 

 foramina open forward into grooves, opposite the front 

 half of M 2 . 



Fig. 6. — Archceotherium davits darbyi, subsp. nov. Holotype. Cat. No. 

 10032. Top view of skull. One-fifth nat. size. F, frontal; J, jugal; L, 

 lachrymal; M, maxillary; N, nasal; P, parietal; P.m, premaxillary ; S.o, 

 supra-occipital; T, temporal. 



The frontals near the border of the orbit are heavy, 

 rugose, folded with a deep central fossa. The narrow edge 

 of the parietal border forward blends into the roughened 

 surface above and behind the orbit. A single, minute, 

 supra-orbital foramen may be seen near the mid-line of the 

 skull. The anterior end of the frontal is broad; on the 

 other hand, the lachrymal is narrow and extends far from 

 the orbit of which it forms only a small part. The jugal 

 sends out a long point on the face, but it is high, and the 

 maxillary actually forms a part of the arch. 



The canine is more strongly recurved and more robust 

 than that of the type of A. clavus clavus. P 1 , like P 2 , is 

 relatively small. P 2 is separated about 16 mm. from P 3 . 



