362 ROY L. MOODIE 
The cerebrum of Aenocyon (Canis) dirus almost obscures the 
cerebellum from a lateral view, so greatly does the neopallium 
overlap the hindbrain. The cerebellum in this ancient wolf 
actually lies in a cavern excavated in the posterior wall of the 
cerebrum and is only evident from a posterior aspect. The 
olfactory bulb in Aenocyon is more straight and does not bend 
so sharply downwards as it does in modern dogs. 
The lateral sulci (S.lat.) of the two hemispheres (fig. 13) are 
unequal in their development and somewhat asymmetric, the 
right suleus being farther away from the median border of the 
hemisphere than the left. Posteriorly, the sulci are associated 
in their origin with the postero-lateral sulcus (S.positlat., figs.13 
and 14). Anteriorly, the lateral sulci are related to the coronal 
(S.cor.) and ansate (S.ans.) sulci (fig. 14), though these last- 
mentioned sulci do not represent direct continuations of the 
lateral sulcus as in many modern Cynoidea, but are related to 
it by a shallow depression connecting the three. The gyrus 
between the lateral sulcus and the median surface of the cerebrum 
is not a continuous ridge, but is interrupted by transverse depres- 
sions, giving the gyrus a bumpy appearance. The sagittal sinus 
is less developed, proportionately, in Aenocyon than in Da- 
phaenus. This decrease in size is to be correlated with the 
growth of the skull and decrease in size of the sagittal crest and 
the growth of the neopallium. 
The postero-lateral sulcus, bilaterally symmetrical, is almost a 
direct continuation of the lateral, the only interruption being a 
broad, shallow depression (fig. 14). Terminal rami of the arteria 
meningea media, clearly evident on the right side of the cast, 
cross the posterior end of the lateral suleus and the postero- 
lateral sulcus. The ectolateral sulcus, equal on the two sides, 
is sharply marked and its arc is parallel dorsally with the lateral 
suleus and posteriorly with the postero-lateral sulcus. The 
suprasylvian and postsylvian forms a similar are within the 
ectolateral. At the upper end of the sylvian depression three 
trunks of the middle meningeal artery are evident. The orbital 
sulcus (S.orb.) is represented by a short depression near the 
olfactory bulb, and it is continued downward posterior to the 
