AND OTHER PARTS OF HIPPOPOTAMUS. 517 
with the coronal fissure. It ends independently, much as in the 
Cavicornia and Swine, with a downward tendency; nevertheless I am 
not able to recognize anything corresponding to the wedge-shaped con- 
volution formed between it and the insignificant superior limb of the 
same fissure, so well marked in the Swine, as above described. 
The fissura splenialis does not curve upwards anteriorly to become 
superficial, as it does in Sus, but continues onwards to blend with the 
fissura genualis, at the same time that it sends up a short perpen- 
dicular fissure about one-third from the anterior extremity of the 
hemisphere, just long enough to be seen upon the surface. There is a 
short vertical sulcus, generally more or less developed in the Ungulata, 
to be noticed, separating the posterior limb of the splenial fissure from 
the corpus callosum, nearer the latter than the former in the present 
case. 
The Sylvian fissure is insignificant, the fissura rhinalis being con- 
tinuous with it before and behind. 
The small size of the optic and the olfactory nerves, and the not 
great development of the corpora quadrigemina, are sufficiently 
emphasized by Gratiolet to require no further mention. 
Tf the view here adopted is not the correct one, and what is above 
described as the lateral fissure is the suprasylvian, then the brain of 
the Hippopotamus differs from that of all allied forms in the immense 
breadth of the interval between the Sylvian and the suprasylvian | 
fissures, a breadth not to be explained upon any known hypothesis, and 
opposed by what is found in Hippopotamus liberiensis. There are no 
analogies, also, in favour of what would then_be the correspondingly 
peculiar narrow interval between the splenial and suprasylvian 
fissures. 
Looked at generally, the brain of the Hippopotamus is evidently Page 16. 
very different from that of the genus Sws and its nearest allies. In the 
great breadth and complicatedness of what, in my paper on the brain 
of the Sumatran Rhinoceros,* I term “the middle oblique convolu- 
tion’ (that between the lateral and suprasylvian fissures), it most 
resembles the Camels and the Giraffe, from the form of which it 
strikingly differs in the much less “ pronation,” as Dr. Krueg terms 
it,t of the hemisphere. On the whole, it stands very much by itself. 
The enormous stomach, with an axial length of 11 feet, is identical 
* “Transactions of the Zoological Society,” vol. X. p. 411. (Supra, p. 143.} 
+ By this “ pronation” or “supination” of the brain is meant the degree of, as 
it were, inward or outward rotation of the surface which allows less or more of the 
surface between the corpus callosum and the suprasylvian fissures to appear super- 
ficially. 
