>. 
AND OTHER PARTS OF HIPPOPOTAMUS. 515 
- backwards and inwards rather than outwards. In my opinion this 
arrangement is better indicated by saying that the descending limb 
of the suprasylvian fissure is developed in the Swine at the expense 
of the posterior, whilst in the Cotylophora the posterior limb is large 
and the descending limb rudimentary. In the Swine, also, the fissura 
rhinalis and the fore-and-aft prolongations of the Sylvian fissure be- 
come continuous. In the Cotylophora they do not unite, the former 
being at a lower level. 
A careful comparison of the brain of Dicotyles tajagu with Dr. 
Krueg’s illustration of the same in D. torquatus does not lead me to 
see that Dicotyles resembles the true Swine so closely as might be 
expected from that author’s sketch. The characteristic descending © 
limb of the suprasylvian fissure is quite wanting in the two specimens 
at my disposal, and its posterior limb turns inwards slightly, as in the 
Cotylophora. There is one upward branch of the splenial fissure Page 14. 
which joins the fissura coronalis, and is not a continuation of it, as in 
Sus. If it were not for this the fissura coronalis and fissura lateralis 
would be continuous in Dicotyles. 
In Sus there is a minor longitudinal fissure between the fissura 
splenialis and the fissura lateralis, or there may be two. In Dicotyles 
it is the same, the outer moiety being the broader. 
The convolution between the fissura lateralis and the fissura 
_ suprasylvia is broader than that between the fissura lateralis and the 
middle line—considerably in Sus, not so much so in Dicotyles. Gyri 
of the included convolution, towards its outer border, make its outer 
contour less distinctly marked than is its inner boundary, and the 
complication may be increased by the presence of transverse bridging 
convolutions. f 
In Dicotyles the superior limb of the suprasylvian fissure termi- 
nates, as in the Swine and Cavicornia, without communicating with 
any other of importance, at the same time that a wedge-shaped con- 
volution is always more or less developed in the region under con- 
sideration, with its backward-directed apex formed by the junction of 
the superior and anterior limbs of the suprasylvian fissure. In the 
Cervide it is the rule that the superior limb of the above-named 
fissure blends with the posterior extremity of the coronal fissure. The 
specimen of Hlaphodus michianus figured by me* does not, however, 
quite conform with this law. 
The adult Hippopotamus brain which forms the subject of this 
communication differs so much in the arrangement of the convolu- 
tions of the two sides, that from a study of one or the other singly 
very different results might be arrived at. This evidently depends 
* “ Proceedings of the Zoological Society,” 1876, p. 757. (Supra, p. 387.) 
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