14 PROF. A. H. GARROD ON THE BRAIN 
one upward branch of the splenial fissure which joins the fissura coronalis, and is not a 
continuation of it, asin 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. 
In Dicotyles the superior limb of the suprasylvian fissure terminates, as in the Swine 
and Cavicornia, without communicating with any other of importance, at the same time 
that a wedge-shaped convolution is always more or less developed in the region under 
consideration, 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 Elaphodus 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 convolutions of the two sides, that from a study of 
one or the other singly very different results might be arrived at. This evidently 
depends upon the considerable development on the right side of bridging conyolutions, 
the great number of which in the brain of the Hippopotamus is laid special strain on 
by Gratiolet?, who, whilst referring to the “ middle series” of convolutions, remarks:— 
“Tl acquiert une importance exceptionelle, et si son existence est au premier abord 
dissimulée, cela tient & la grande quantité de plis de passages verticaux qui lient cet 
étage supérieur a l’etage inférieur proprement dit.” On the left side these bridging 
convolutions do not exist, and as a result an extra longitudinal fissure is seen, which 
must be one of the typical sulci of the cerebral hemisphere, it being conspicuous in the 
brain of Hippopotamus liberiensis, according to Prof. Macalister’s outline sketch, though 
absent in the figures accompanying Gratiolet’s memoir on H. amphibius. 
The brain of the Hippopotamus is not richly convoluted. It is about as much 
so as that of the genus Bos, decidedly less so than Camelopardalis givaffa or the 
Camelide. The considerably smaller Rhinoceros, Ceratorhinus swnatrensis*, has more 
convolutions. 
Its weight immediately after removal from the skull was one pound and seven ounces. 
The most conspicuous fissure on the superior surface of the brain is one running from 
? P.Z.8. 1876, p. 757. * Anatomie de l’Hippopotame, p. 325. 
* Trans. Zool. Soe. vol. x. pl. lxx. p. 411. 
