ARTIODACTYLA. 
339 
and are rather narrower anteriorly than posteriorly. They contract poste¬ 
riorly from the Sylvian convolution. The profile descends gradually to the 
olfactory lobes. The superior surface is little convex in the tiunsverse 
direction. The fissure of Sylvius is nearly vertical in position, and its 
superior extremity is visible from above. A strongly-marked fissure extends 
posteriorly from it, defining the lohus hippocampi above. The Sylvian con¬ 
volution is the thickest of all, and its outer border is emarginate in front 
and behind. Below the postero-superior emargination, it is thickest and 
most protuberant. Between it and the position of the falx, there are three 
longitudinal convolutions, the external, the median, and the internal. These 
are slightly divergent posteriorly, but the posterior extremities of those of 
one side tend to unite on the posterior border of the hemisphere. Their 
surfaces are smooth. The external is widest medially, and it terminates 
anteriorly just behind the apex of the Sylvian convolution. The internal 
is double posteriorly. The median is simple, and unites with the internal 
above the apex of the Sylvian convolution. The two conjoined continue 
for a short distance, and terminate in a broad tuberosity. Below the external 
convolution, on the side of the posterior part of the hemisphere, there are 
four small longitudinal convolutions. The orbital portion of the hemispheres 
is extensive, and nearly smooth from the olfactory lobes to the supraorbital 
border. This is not prominent, but is represented by a short longitudinal 
ridge. Above each of these, on the superior or front aspect of the hemi¬ 
spheres, is a massive convolution, bent crescent-shaped, with the convexity 
inward. The posterior part of the convolution is a subround tuberosity, 
which stands opposite to, and in front of, the furrow separating the Sylvian 
and median convolutions. The middle part of the crescent is less promi¬ 
nent, but the anterior extremity forms another tuberosity, whose long axis 
is directed downward and outward. The crescentic convolution of the one 
side is separated from that of the other by a wide, shallow, median, longi¬ 
tudinal groove, which extends transversely at the posterior tuberosities^ 
The two tuberosities and the olfactory lobes form three descending steps. 
As compared with the brains of the existing Bovidcc, that of the Procam- 
elus differs in the forms of the cerebellum and medulla oblongata, as already 
pointed out. The hemispheres differ in being shorter behind and more de- 
