Page 13. 
514 ON THE BRAIN 
middle line,of the hemisphere into two equal parts. The presylvian, 
diagonal, and posterior fissures, though they appear on the superior 
surface, are so much better seen in the lateral view of the brain that 
they will be there described. 
The inner aspect of the hemisphere presents, besides the hippo- 
campal fissure (i), a long fisswra splenialis (sp), or calloso-marginalis, 
some distance from the superior margin, curved concavely towards 
the corpus callosum, opposite the hinder end of which its posterior 
extremity ceases, whilst anteriorly it continues nearly as far forward 
as the perpendicular level of the genu of the corpus callosum, which 
is partly embraced anteriorly, as it were, by a small fisswra genu- 
alis (q). 
The outer aspect of the hemisphere has a basal fissure running 
nearly its whole length—the fisswra rhinalis (rh), some little distance 
above which the anterior and posterior limbs of the Sylvian fissure 
(sa and sp) diverge, the hinder extremity of the latter sending down- 
wards an extension to meet it. The anterior end of the anterior limb 
of the Sylvian fissure also joins the posterior extremity of the small 
presylvian (ps) fissure, concave upwards, situated low down in the 
outer frontal region, with another small and very similar diagonal 
fissure (d) half way between it and the coronal fissure (co). The 
fissura postica (p) is a small one between the hinder part of the fissura 
rhinalis and the posterior limb of the supra-sylvian fissure. 
So much for the typical cerebral convolutions in the Ungulate 
animal, which undergo special modifications in the different families 
of the order, some of which are particularly constant, and must be 
here referred to in order that comparisons may be made between the 
Hippopotamus and its allies. 
The brain of the genus Sus, together with Phacocherus, is distin- 
guishable from that of any other Artiodactylate animal by one or two 
well-marked characters, the most striking of which is the blending of 
the coronal with the splenial fissure by means of a curved sulcus of so 
considerable a depth that the convolution between the middle line of 
the hemisphere and the coronal fissure appears to be quite cut off 
from the rest of the superior cerebral surface. The presylvian fissure, 
however, as usual, runs up on the inner side of the outward-directed 
anterior extremity of the coronal fissure. Behind the sulcus of com- 
munication between the fissures just referred to there is always an 
equally characteristic second one, parallel to it, and a short distance 
behind it, joining the fissura splenialis and a prolongation of the 
superior limb of the suprasylvian fissure. Again, as Dr. Krueg 
puts it, the posterior extremity of the suprasylvian fissure turns 
downwards on the outer side of the hemisphere, and ceases near 
the lower border of the brain; whereas in the Cotylophora it runs 
