OF THE SPERM WHALE. 
Ill 
the bulk of the animal. In the porpoise I believe it is 
the largest, and, perhaps, in that respect comes nearer 
to the human. The size of the cerebellum in propor- 
tion to that of the cerebrum, is smaller in the human 
subject than in any animal with which I am acquainted. 
In many quadrupeds, as the horse, cow, etc., the dispro- 
portion in size between the cerebellum and cerebrum is 
not great, and in this tribe it is still less, yet not so 
small as in the bird, etc. The whole brain in this tribe 
is compact, the anterior part of the cerebrum not pro- 
jecting so far forward as in either the quadruped or 
human subject, neither is the medulla oblongata so pro- 
minent, but flat, lying in a kind of hollow, made by the 
two lobes of the cerebellum. The brain is composed of 
cortical and medullary substances very distinctly marked, 
the cortical being in colour like the tubular substance of 
a kidney, the medullary very white. These substances 
are nearly in the same proportion as in the human 
brain. The two lateral ventricles are large, and in those 
that have olfactory nerves are not continued into them 
as in many quadrupeds, nor do they wind so much out- 
wards as in the human subject, but pass close round the 
posterior ends of the tlialami nervorum opticorum. The 
thalami themselves are large. The corpora stiata small, 
the crurse of the fornix are continued along the winding 
of the ventricles much as in the human subject. The 
plexus choroides is attached to a strong membrane, which 
covers the thalami nervorum opticorum, and passes 
through the whole course of the ventricle, much as in 
the human subject. 
