338 
ARTIODACTYLA. 
Brain. —This organ displays the characters of the older types of Rumi- 
nantia, although not materially smaller than that of the Llama, an animal 
which it equaled in general proportions. The hemispheres are, however, not 
produced so far posteriorly in the Procamelus as in the Auchenia, reaching 
only to the line of the meatus auditorius externus in the former. The vermis 
of the cerebellum rises abruptly from the medulla, having a nearly vertical 
direction to a point a little lower than the superior plane of the hemispheres. 
The lateral lobes extend on each side of it, each one having a rather greater 
width than the vermis. Their posterior faces are subvertical, and are 
directed slightly forward. Each projects laterally into an apex at the mid¬ 
dle of its elevation, and then contracts downward into the angular line 
which marks the posterior border of the petrous bone. From a point 
between each apex and the vermis, a ridge rises obliquely inward to the supe¬ 
rior plane of the cerebellum, where each one enlarges and joins the median 
transverse line. The angle above described as descending from the lateral 
apex of the cerebellum curves forward, forming a lateral angular border of 
the pons varolii on each side. The flat space inclosed between this line and 
the posterior border of the hemisphere is interrupted by two prominent tuber¬ 
osities. The superior is small and suboval, and is near to the posterior bor¬ 
der of the hemisphere. The other is a short, prominent ridge, directed 
downward and forward, just behind the lobus hippocampi. Its inferior end 
con’esponds with the origin of the mandibular branch of the trigeminus and 
perhaps the facial nerve. 
The medulla oblongata is contracted at the foramen magnum, and has a 
subround section slightly flattened below. Its inferior face is then rounded, 
then flattened, and then concave between the anterior part of the lateral 
ridges. The bases of the maxillary branches of the trigeminus nerves are 
stout, and directly in line with the origins of the mandibulars. Between 
them, the base of the brain is concave, and the optic nerves issue but a little 
distance in front of them. The lobi hippocampi are subround and rather 
prominent. They are terminated in front at the foramen sphenobrbitale by 
the contraction of the cranial walls. Their surface displays slightly-defined 
convolutions, the best marked being inferior and subround in form. 
The cerebral hemispheres, viewed from above, have an oval outline, 
