AND OTHER PARTS OF HIPPOPOTAMUS. 13 
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 ante- 
riorly, as it were, by a small fisswra genualis (q). 
The outer aspect of the hemisphere has a basal fissure running nearly its whole length 
—the jissura 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 
downwards an extension to meet it. The anterior end of the anterior limb of the syl- 
vian fissure also joins the posterior extremity of the small preesylvian (ps) fissure, concave 
upwards, situated low down in the outer frontal region, with another small and very 
similar diagonal fisswre (d) half way between it and the coronal fissure (co). The 
Jissura 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 distinguishable 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 communication 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. Kreug 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 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 become continuous. In the Cotylophora they do not unite, the former being at 
a lower level. 
A careful comparison of the brain of Dicotyles tajagw with Dr. Kreug’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 
