17G ON THE EXTINCT MAMMALIA OF 



its back border more vertical. The outline of the base is interrupted by a pair of 

 bony knobs, and the symphysis is less slanting. The canine teeth do not project 

 internally, and resemble more those of the carnivores than those of living suilline 

 animals. 



In the upper view of the skull of Eloiherium Mortoni it actually bears more resem- 

 blance to that of the great felines, the Lion or Tiger, than to that of its natural ally, 

 the Hog. The cranium is proportionately shorter, narrower posteriorly, and much 

 less capacious than in the Lion, but its sides occupied by the capacious temporal 

 fossae, separated by the high sagittal crest, and defined below by the wide outstretch- 

 ing zygomatic arches, give it a wonderful resemblance to that of the latter animal. 

 The face is proportionately much longer than in the Lion, both in relation with its 

 breadth and height, and with the length of the cranium. The forehead is much 

 wider and longer, and the orbits are more vertical and much less directed forward. 



In some respects the skull of Ehtherium Mortoni resembles that of the Hippopota- 

 mus more than it does that of the Hog. Thus E. Mortoni resembles Hippopotamus 

 in the separation of the temporal fossas by a sagittal crest, in the wide expanse of its 

 zygomatic ai'ches, in its more cylindroid face, and in the short termination of the 

 nasals. 



Lateral view of the slcull. — The upper outline of the skull, as seen from its side, 

 represented in plate XVI, presents a moderate and almost uninterrupted slope from 

 the rounded summit of the inion to the end of the nose. The occipital outline is 

 neai'ly like that of the Hog, prominently convex above and concave below, ending 

 nearly perpendicularly with the condyles. The muzzle is pointed, but the slope of 

 the nose is oblique as in the Hippopotamus or the Bear, and the slope of the 

 mandibular symphysis is not very different from that of the latter animal. 



The temporal fossa has a capacity in its proportions and form more resembling that 

 of carnivores than that of the ordinary suillines. Among the latter it is most like 

 that of the Hippopotamus, especially of Choerodes, or the small Hippopotamus of St. 

 Paul's River, Western Africa. Besides being of greater capacity than in the latter, 

 it is proportionately longer and not quite so deep. 



The temporal surface rises upon a strong sagittal crest, which is not greatly 

 exceeded in its proportions by that of the Hytena. Posteriorly it forms a broad slope 

 outwardly to the acute margin of the inion and the deep posterior root of the zygoma. 

 Its long diameter is fore and aft, instead of being obliquely downward and forward as 

 in the Hog. 



The zygoma at its posterior root projects directly outward to a greater extent than 

 in the Hog. Bending abruptly forward, as in the latter animal, it then ascends 

 inwardly towards the fiice as in the Hippopotamus. It is remarkable for its great 



