555 
with. This recess, from its position and curvature, must, I think, 
be regarded as a rudimentary posterior cornu. As the soaking of 
a brain in spirit, for a series of years, has a tendency to render the 
examination of the ventricular arrangements more difficult, than 
would be the case in a recent brain, I hope, in the course of the 
summer, to supplement this observation, by an examination of the 
brain of the common porpoise. 
In the brains of those Carnivora which I have been able to examine, 
the cerebellum has been seen to possess tentorial and occipital surfaces, 
separated by a slight, yet definite, ridge, which corresponded to the 
line of attachment of the tentorium to the occipital bone. The cere- 
bellum is not, however, so decidedly a “ cerebellum inferius” as in the 
examples already described. The surfaces of the cerebellum con- 
sequently look more or less forwards and backwards. Thus, if we 
look from above upon the brain of a dog or cat, we see the cerebellum 
projecting slightly behind the cerebrum, or exposed, as it is usually 
stated. From the description which has been given by Tiedemann* 
of these relations, not only in the Carnivora, but in the Ruminantia, 
Solipeds and Pachydermata, it is evident that he considered a por- 
tion, at least, of this exposed surface belonged to the anterior aspect 
of the cerebellum. But if we examine the brain in situ , we shall 
see that the posterior end of the cerebrum passes as far as the 
posterior margin of the anterior (tentorial) surface of the cerebellum, 
so as to cover it. The exposed surface is, therefore, the occipital, or 
that which corresponds to the inferior surface of the human cere- 
bellum. In the dog, both the tentorial and occipital surfaces of the 
cerebellum are well developed and about equal in extent. The 
amount of cerebral hemispheres in relation, through the tentorium, 
to the corresponding cerebellar surface, is therefore considerable, 
and warrants us, I think, in regarding them as posterior lobes. 
The lateral ventricles do not possess any proper posterior cornua ; 
but a slight indentation, continuous with the ventricular cavity, in the 
substance of each posterior lobe, appears to me to present a rudi- 
ment of the posterior horn. In the cat, the tentorial is smaller 
than the occipital surface of the cerebellum, and the extent of 
cerebrum in relation with it is proportionally smaller than in the 
dog, so that the size of its posterior lobes is smaller ; for the area of 
* Anatomie und Bildungs-geschichte des Gehirns, &c. Niirnberg, 1816. 
P. 147. 
4 F 
yoL. lv. 
