74 ON THE EXTINCT MAMMALIA OF 



The cranium is constricted, and is narrowest immediately behind the expansion of 

 the forehead to the post-orbital arches. Posterior to the constriction it is ovoid, but 

 expands in an elevated acute border and prominent obtuse summit to the inion, and 

 in a long median sagittal crest. 



The temporal fossce extend about half the length of the skull, and are separated by 

 a strong sagittal crest. Their depth, where greatest, corresponding with the posterior 

 root of the zygoma, is about half their length. 



The sagittal crest, long, narrow and high, resembles that of the Camel family, or 

 that more frequently observed among carnivorous animals. It commences in a tri- 

 angular expansion at the broad summit of the inion, and usually reaches to the 

 commencement of the frontal bone, corresponding with the narrowest portion of the 

 cranium, before it bifurcates. 



The temporal ridges, defining the forehead from the temporal fossae, curve out- 

 wardly to the post-orbital arches in the same manner as in the Camel family. 



The temporal sui-face of the cranium has the usual triangular outline, with its apex 

 curving outwardly on the post-orbital process of the frontal bone. Independently of 

 the elevation of its borders, it is convex. In some skulls it is more or less abruptly 

 depressed along the parietal border just in advance of the fore part of the tempero- 

 parietal suture, giving rise to the appearance of a curved groove. At the back part 

 of the tempero-parietal suture, but piercing the edge of the parietal bone, there is a 

 large venous foramen, sometimes replaced by a pair of smaller ones. In some skulls 

 the foramina piei'ce the parietal bone a short distance above the suture indicated. 



The zygomata enclose a space intermediate in extent proportionately to that in the 

 Camel family and some of the carnivora. They are proportionately stronger than in 

 the Camel, and are more arched upward and more convex externally. Their 

 posterior root above contributes a broad triangular surface to the temporal fossae. 

 Their course from the posterior root is outward, and then downward and forward to 

 the face. They are proportionately of greater depth than in the recent ruminants 

 and carnivora, and approach in this respect the Peccary. 



The inion or occipital extremity of the cranium is intermediate in form to that of 

 the last mentioned animal and that of the Wolf It is triangular, with a broad 

 convex summit and lateral sigmoid borders, ending in the large paramastoid processes 

 which form the basal angles of the triangle. 



The summit of the inion is produced backward on each side, as in the Peccary, in 

 strong wing-like processes, terminating below by bifurcating into the prominent acute 

 lateral border of the inion, and an obtuse ridge descending and expanding upon the 

 occipital surface above the condyle. Between the ridge just indicated and the lateral 

 border of the inion there is a deep fossa, expanding below upon the base of the para- 



