O74 NOTES ON THE CANIDE OF THE WHITE RIVER OLIGOCENE. 
TWO “Weas) eestor (Ie 2s, Itinee, 114), 
The brain of Cynodictis has already been described by Bruce (’83, p. 41), but as I 
wish to consider it from a different standpoint, some account of it will be necessary. In 
this genus the brain is relatively smaller than in any of the recent Canidw. The olfac- 
tory lobes are large and are left exposed by the hemispheres, with which they are con- 
nected by short and thick olfactory tracts. The cerebral hemispheres are pear-shaped, 
broad behind, but tapering rapidly forward, where they decrease in vertical as much as 
in transverse diameter. The frontal lobe is short, narrow and of small vertical depth, 
while the parietal lobe much surpasses it in every dimension ; a transyerse depression 
marks the boundary between the two. The temporo-sphenoidal lobe is also quite well 
deyeloped and adds materially to the dorso-ventral diameter of the brain in this region. 
Posteriorly the hemispheres slightly overlap the lateral lobes of the cerebellum (which 
appears not to be the case in Daphwenus), but leave the yermis entirely uncoyered. The 
shape of the cerebrum is thus alopecoid rather than thooid in character. In the former 
series the hemispheres are wide behind and taper anteriorly, with slight incurvations at 
the sylvian and presylvian fissures, while in the thooids the cerebrum is narrower behind 
and at the presylvian fissure the sides are abruptly incurved almost at a right angle ; 
the frontal lobes are much larger relatively than in the foxes (see Huxley, ’80, pp. 245— 
247). The hemispheres of Cynodictis agree well in shape with those of the alopecoids, 
and when compared with the brain of the later and more adyanced genus Cynodesmus 
from the John Day, the greater width of their posterior region is distinctly to be seen. 
The whole character of the skull makes it evident that Cynodesmus is a thooid, while 
both brain and skull structure approximate Cynodictis more to the alopecoids. 
The hemispheres are very simply conyoluted and the sulci are few, simple and short, 
though it should not be forgotten that the brain-cast very probably fails to reproduce all 
of the fissures. In the recent Canide the conyolutions are numerous and complex, and 
the sulci pursue a remarkably curved course, giving to the conyolutions, when seen from 
the side, the appearance of a succession of U-shaped, concentric coils, grouped around 
the sylvian fissure as a centre. In Cynodictis, on the other hand, the visible sulci are 
few, shallow, short and nearly straight. On the dorsal surface of the hemisphere only 
two fissures are to be observed, the lateral and the suprasylvian, the former of which is 
short and almost straight, dying away before it reaches the hinder part of the parietal 
lobe. If the coronal sulcus is present at all, it is in the same fore-and-aft line as the 
lateral, and has not the outward sweep around the crucial fissure which is so characteris- 
tic of Canis. No trace of the crucial fissure is preserved in the brain-cast, and if it was 
present in the brain, it must haye been short, as is indicated by the straight course of the 
