90; 
NOTES ON THE CANID® OF THE WHITE RIVER OLIGOCENE. OOo” 
The mandible differs considerably in the yarious species, though the comparison 
between them can as yet be but partially made, for the only specimen known to me in 
which the angle and coronoid process are preseryed, is that figured by Leidy (/. ¢., Pl. I, 
Fig. 2), which belongs to D. vetus. In ? D. dodgei (Pl. XIX, Figs. 6, 7.) the horizontal 
portion of the mandible is thick, heavy and relatively short; the inferior border is very 
far from straight, rising beneath the masseteric fossa almost to the level of the molars and 
descending forward from this point in a bold, sweeping curve, quite as in the modern 
Canis aureus ; the masseteric fossa is very deep and its ventral border forms a prominent 
ridge, distinct from the lower border of the jaw; the symphysis is short and the chin 
abruptly rounded and steeply inclined. 
In D. vetus the horizontal ramus is of an entirely different shape (see Pl. XTX, 
Fig. 5) being longer, more compressed and slender and with a decidedly straighter 
ventral border; the symphysis is longer and the chin more gently rounded, rising more 
gradually from the inferior margin of the ramus. The masseteric fossa is quite deeply 
impressed, though less so than in ? D. dodge, and is very large, extending far up upon 
the ascending ramus. The angle is a stout hook, which is less elevated above the general 
level of the horizontal ramus than in modern wolves or foxes. The condyle also has a 
low position, below the level of the molars, while in recent species the condyle is raised 
above the molars, and in some species very much so. The ascending ramus has great 
antero-posterior extent, by which the condyle is remoyed far back of the last molar. 
This is a primitive feature which recurs in most creodonts and is evidently correlated 
with the characteristic elongation of the cranium and zygomatic arches. The coronoid 
process is high and wide, and has a bluntly rounded end; it inclines much more strongly 
backward than in Canis and has a much more concave posterior border. The condyle 
resembles that of the recent dogs, but is set upon a more distinct neck, is more extended 
transversely, and is less cylindrical in shape, tapering more toward the outer end. 
In D. hartshornianus the mandible, so far as it is preseryed in the various speci- 
mens, resembles that of D. vetus, save that the horizontal ramus is somewhat shallower 
and more slender. 
The Brain. Very little can be said concerning the brain, since no complete cast of 
the cranial cavity is available for study. The general shape and development of the 
brain are, however, indicated in the specimen of D. hartshornianus already described 
(Pl. XIX, Fig. 1). Its proportions are very different from those found in existing 
members of the family, a difference which may be briefly stated as largely consisting in 
the much greater relative size of the cerebral hemispheres and smaller size of the olfac- 
tory lobes in the modern species. In Daphenus the brain is narrow and tapers 
rapidly toward the anterior end; the cerebellum and medulla oblongata are long, the 
A. P. S.—VOL. XIX. 2Q. 
