CENTRAL NERVOUS SYSTEM IN VERTEBRATE ANIMALS. 
763 
spinal cord of Scorpcena distinctly break up into fibrillse for a short distance, and then 
resume its original appearance. 
The ventral longitudinal column rises up gradually from contact with the lower 
surface of the medulla (fig. 1), and the central longitundal column joins it beneath 
the posterior part of the cerebellum, beyond the decussation of the Mauthner’s fibres ; 
which decussation is not participated in by the accompanying bundles. 
The combined columns pass straight forward and are lost in the internal part of the 
floor of the optic lobe at about the posterior end of the third ventricle. 
The columns situated on each side of the central portion of the substantia gelantinosa 
centralis, which may be termed the lateral columns (fig. 12, l.c.), pass forward and are 
lost in the floor of the optic ventricle near to but outside the last-mentioned columns. 
At the point where the ventral longitudinal bundles rise up towards the dorsal 
surface, other fibres are substituted for them along the ventral and lateral borders of 
the medulla. The more lateral of these, as before mentioned, pass into the commis- 
sura ansulata ; those in the mid-line, however, pass into the posterior end of the 
hypoarium through the commissura ansulata, and curve over the anterior end of the 
furrow between that body and the medulla. 
Anterior Crura Cerebelli. (Fig. 24.) 
There are three bundles of fibres which may be collectively termed the anterior 
crura cerebelli, since they pass out of the cerebellum and then turn forward. 
The most anterior extending downwards and forwards beneath the anterior layer of 
the Purkinje cells of the cerebellum, immediately turns forwards and is lost in the 
lateral wings of the valvula cerebelli. 
The most posterior of the three bundles passes obliquely downwards and forwards 
towards the hypoarium and is lost near the outer side of the “ nucleus rotundus ” of 
that lobe. 
The middle cord of the anterior crura cerebelli is the largest of the three ; it separates 
into two divisions at the base of that section of the brain. The superior division 
enters the lateral wing of the valvula cerebelli beneath the anterior bundle of the 
crus. 
The other division, which is the main body of this bundle, enters the deeper parts 
of the torus, and then making a gentle curve with the concavity turned upwards, it 
enters the fourth layer of the tectum ; this may be looked upon as the processus 
e cerebello ad testes. 
Many bundles of fibres are derived from the deep commissure which was described 
with the transverse commissures of the brain ; of these one passes off when it arrives 
at the superior edge of the “ nucleus rotundus.” This bundle on leaving the above- 
mentioned commissure borders the posterior margin of that body, and is joined at the 
lower edge by several small bundles of fibres, which leave the deep commissure in the 
