412 MR. A. H. GARROD ON THE BRAIN OF THE SUMATRAN RHINOCEROS. 
in the Equidi, as might have been surmised. The whole brain, however, is broader, 
especially near the posterior portion of the cerebral hemispheres, where the breadth is 
considerably greater than further forward. 
The accompanying diagram will facilitate the description. 
It represents the disposition of the main convolutions upon 
the superior aspect of one hemisphere, and exhibits the 
direction of the sulci which divide them. Two diagonal sulci 
cut up the posterior part of each lobe into three oblique 
gyri, which may be called the (1) external, (2) middle, 
and (3) internal gyrus. The middle and internal of these 
fuse together near the transverse line which joins the two 
rudimentary Sylvian fissures, anteriorly to which there is, 
in the Equide, no indication of further primary longitudinal 
division. The external oblique gyrus continues, from this 

line, directly forwards, and independent. 
In Ceratorhinus sumatrensis the internal oblique gyrus Upper view of left cerebral 
hemisphere of Ceratorhinus 
sumatrensis, showing general 
direction of sulci. 
is triangular in shape, its inner boundary being the great 
longitudinal fissure of the hemispheres, into which it de- 
scends a short distance. In the Equide the inner boundary 
of this gyrus is more superficial, and can be seen as a straight longitudinal line, 
just external to the fissure itself, in the superior view of the brain. The whole gyrus 
is much broken up by minor foldings of its elements, especially in its median portion, 
its outer moiety consisting of a minor gyrus, whose general direction is a continuous 
oblique line, fairly regularly bent upon itself, first one way and then the reverse. 
The median oblique gyrus is divided into two nearly equal moieties by a fissure 
running parallel to its direction, each half being much doubled upon itself. Anteriorly 
bridging minor convolutions blend it with the internal oblique gyrus, about one third 
distant from the anterior extremity of the hemisphere, in front of which the broad 
oblong cerebral surface is divided by a longitudinal sulcus into two equal moieties, 
both convoluted. In the great breadth and division of this anterior portion the 
Rhinoceros under consideration differs from the Equide, and agrees with Rhinoceros 
unicornis. 
The external oblique gyrus is much doubled on itself, and separated from the 
Sylvian fisstre, which it surrounds, by minor convolutions, more strongly differentiated 
anteriorly. 
On the inner surface of the hemisphere the hippocampal gyrus is seen to be traversed 
by minor sulci and slight folds which run parallel to its length, as in the Equide, the 
calloso-marginal sulcus following the anterior bending of the corpus callosum, and 
not, as in so many Artiodactyla (but not in the Equide), becoming superficial 
anteriorly, 
