100 MEMOIRS OF THE CARNEGIE MUSEUM 



The Skull, Plate XV. 



The skull is about one fourth smaller than that of Daphcenus felinus and is of 

 about the same size as that of D. hartshornianus. Seen from above it appears broad 

 and short, with a relatively very large brain-case and broad frontals when compared 

 with Daphcenus or Proamphicyon. Throughout the anterior two thirds of its length 

 the' sagittal crest is reduced to a low sharp ridge rising just above the surface of the 

 brain-case, as shown in PI. XV., Figs. 1 and 2, in marked distinction from the con- 

 ditions that obtain in this region in the two preceding genera. Posteriorly the 

 sagittal crest is higher and unites with the high and sharp occipital crest which 

 overhangs the occipital condyles. The frontals are broad and bear rather prominent 

 and rugose postorbital processes from which superciliary ridges extend, converge 

 and meet posteriorly at an acute angle to form the low, sharp sagittal crest. There 

 is a marked lateral constriction in the facial region midway between the canine 

 and the infraorbital foramen. The anterior process of the frontals is xiot so widely 

 separated from the posterior projection of the premaxillaries as in Daphcenus. The 

 nasals are rather broad anteriorly and bluntly pointed posteriorly. The premaxil- 

 laries are small and there is a constriction between the canine and I.-^ for the accom- 

 modation of the lower canine. 



Seen from the side the top of the skull appears nearly flat longitudinally with 

 the facial region perhaps a little more elongate proportionately than in the preced- 

 ing genera. The zygomatic arches are very slender and but moderately expanded. 

 Posteriorly they do not expand so abruptly from the margins of the skull as in 

 Daphcenus. The postglenoid processes are directed downward and slightly forward 

 while the paroccipital processes point downward and backward at an angle of about 

 forty-five degrees. The foramen magnum is broader than deep, as in modern dogs, 

 although these proportions may have been materially altered by crushing. 



Seen from below the palate appears broad and proportionately somewhat longer 

 than in DajpliGenus and Proamphicyon. The anterior palatine foramen is small. The 

 anterior border of the posterior nares is a little posterior to the last molar. The 

 pterygoid plates are continued far back and arch inward in such manner as to par- 

 tially enclose the narial passage in this region, which in life was doubtless cov- 

 ered over inferioiiy by a membrane. The foramen ovale and posterior opening of 

 the alisphenoid canal have a common opening. The foramen rotundum, sphenoidal 

 fissure and optic foramen are present, but the skull is too much crushed in this 

 region to determine their character with certainty. As in Daphcenus the auditory 

 bullse are not preserved, doubtless through imperfect ossification. The periotic is 

 present and is inflated to accommodate the cochlea. The postglenoid, condylar. 



