ANATOMY OF THE CAT. 
359 
Class, ... Mammalia. 
Order, ,,, Praedacea. 
Section,,, Carnivora. 
Family,,, Felidae (Digititradce), 
Genus,, .. Catus. 
Species, ,, Catus Domestica. 
In the cranium of this animal there exists a curious peculiarity 
when compared with man and other animals; and I wish to 
point out this fact to the comparative anatomical student. If he 
refers to the parietal bone of this animal, he will find a beau¬ 
tiful process of bone, about one-eighth of an inch, and in some 
half an inch wide, extending into the cavity of the cranium, thus 
dividing it completely into two cavities: the larger or anterior 
I denominate the cerebral, from its containing the cerebrum; 
and the lesser or posterior contains the cerebellum, and, not 
having found it described in the works on comparative anatomy 
I possess, I name it the tentorial process of the parietal bone, 
for this very obvious reason, that, when the two parietal bones are 
united together, they form and answer all the pui'poses of the 
membranous tentorium in the human subject.It is ossified at 
veiy early stage of utero-gestation ; this I have found from actual 
dissections of pregnant cats, whom I strangled, and on whom 
I afterwards performed the caesarian operation; and to those 
who never witnessed the fact, a more beautiful anatomical and 
physiological illustration cannot be witnessed than the circu¬ 
lation of the blood—the collapsed state of the lungs, gorged 
with venous blood—the systole and diastole of the heart—the 
peristaltic motion of the intestines—and lastly the foetuses in 
utero—and the enormous tortuous venous sinuses on the surface 
of the uterus, which, like the same organ of most animals, is bi- 
corned, and between the cornua, just above the os uteri in the 
uterus, is a small membranous septum: the uterus is of a grey¬ 
ish-blue colour, caused, I have no doubt, by the numerous blue 
veins which ramify through its substance. The placentae are cir¬ 
cular, and completely envelope the foetus, which may be seen in 
motion at a very early period of its pregnancy. In the foetus, the 
thymus gland is large and similar in shape to the human subject; 
the bones of the head are completely closed at birth, and the eyes 
of the foetuses, previous to and after the formation of the fur, are 
covered by a membrane, which, from a cursory view, appears 
transparent, but rendered of a greyish colour, by the dark hue of 
the eye beneath. The cells of the ethmoidal bone are horizontal, 
and form a great extent of surface for the ramification of the 
* In the dog, an osseous and a membranous tentorium exists; but, with 
the Editor’s permission, I will embrace the peculiarities of the canine family 
on another occasion. 
