ENDOCRANIAL ANATOMY OF FOSSIL MAMMALS a00 
The lateral aspect of the natural endocranial cast is especially 
instructive and is noteworthy on account of the slight develop- 
ment of the cerebral sulci and gyri. A future complexity of 
pattern is suggested for the descendants of this cat, and is to be 
seen in Smilodon (fig. 16). The sylvian fossa is represented by 
a widely opened depression, the borders of which merge gradually 
with the adjacent sulci. The floor of the fossa is perfectly 
smooth. 
Casts of three cranial foramina indicate the positions of only 
three of the cranial nerves, i.e., the optic, the trigeminal, and 
the auditory. The optic nerve is placed well forward, the part 
represented doubtless being subsequent to the chiasma. The 
trigeminal, as indicated by the canal, was a large nerve, but 
presents no unusual characters. The acoustic is represented by 
a partial cast of the internal acoustic foramen and its short canal. 
Unfortunately, the basis cerebri is too imperfect for description. 
mm. 
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Undetermined carnivore, possibly Hoplophoneus. It is singu- 
larly unfortunate that I am unable to positively identify the 
best-preserved brain cast in my possession, but it was not 
accompanied by skeletal parts. It is by far the most beautifully 
preserved cast I have ever seen. I submitted it to Doctor 
Matthew for an opinion, and he thinks it may be a felid, related 
to Hoplophoneus or Dinictis. Since I have already described the 
brain of Dinictis (figs. 3 and 4), the identity of which was ren- 
dered certain by accompanying skeletal parts, I conclude that 
the present cast may be some species of Hoplophoneus. This is 
rendered more probable by comparing the cast with the figures 
of the brain cast of Hoplophoneus given by Bruce (’83), where a 
close resemblance is seen. Then another interesting fact is that 
Hoplophoneus has a high sagittal crest which in other forms 
tends to an exaggerated development of the superior sagittal 
sinus. The present cast (figs. 9 and 10) has such an exaggerated 
