918 THE WHITE RIVER FAUNA. 



Amphicyon cuspigerus. It has no reverted lip at the meatus as in most 

 recent dogs. The basioccipital is wide and rather flat There is a faint 

 median ridge posterior to the middle of the bullae, which has behind, on 

 each side, a shallow concavity, which is much less marked than in the 

 Amphicyon cuspigerus, but which is not represented in Galecynus geismarianus. 

 The fossa between the occipital condyle and the paramastoid process is 

 deep. The zygomata are broken off, but enough remains to show that they 

 are compressed, and have a lateral masseter surface, which occupies half 

 the width of the malar process. 



Sutures. — The ascending process of the premaxillary is long and slender, 

 but does not reach the acuminate anterior process of the frontal. The nasal 

 bones are narrow, and their posterior suture forms an acute angle above the 

 very anterior part of the orbit. 



Foramina. — The nareal oritice is oblique and about as wide as deep. 

 The infraorbital foramen is large, and is over the anterior root of the supe- 

 rior sectorial. The meatus aucUtorius externus is large, and has a narrow 

 extension downwards and forwards. The condyloid foramen is, as in recent 

 Canis, anterior to the transvei'se ridge extending to the paroccipital process, 

 and is small, and quite near the foramen lacerum posterins. The bulla is 

 closely appressed to the sphenoid, so that the/ I. anterius is of very small 

 size. The other foramina are still concealed by matrix. The posterior or 

 nareal border of the palate forms two shallow concavities. 



Dentition. — The superior incisors have simple crowns, and the median 

 ones are very small. The crowns of the canines are slender, acute, and 

 with an oval section. The second and third superior premolars have a 

 posterior cutting lobe, though that of the anterior is very small. The sec- 

 torial is small and robust. It has a basal cingulum both internally and 

 externally. The tuberculars are moderate, the anterior narrower internally 

 than externally, the second of equal width at both ends. Their tubercles, 

 external cingulum, median V-shaped ridge, and internal cingulum are well 

 developed. The three posterior inferior premolars have a well-marked 

 posterior marginal lobe. The sectorial has no external tubercle at the pos- 

 terior base of the principal cusp. No external cingula on the inferior 

 molars. 



