426 J. B. JOHNSTON 
arations. In Weigert sections the fibers appear to lose their 
myelin as they enter the dorsal ridge but a small number of 
medullated fibers are seen running right through the ridge into 
the pallium (fig. 32). There is at present insufficient evidence 
to show what proportion of the non-medullated fibers of the 
sensory bundle reach the pallium but it is clear that a large 
part of them do so. When transverse sections are followed from 
behind forward it is seen that the coarse-fibered sensory bundle 
all rises to the pallium or the ventricular ridge and disappears 
from the sections before the rostral end of the ridge is reached. 
The distribution of fibers to the caudal pole of the pallium is 
partly through the base of the ventricular ridge and partly by 
way of the fiber-layer of the pallium itself. Very few medul- 
lated fibers reach the caudal pole. 
The ventral, fine-fibered bundle spreads laterally in the super- 
ficial part of the striatum (nucleus lentiformis) and rises toward 
the lateral border of the pallium. The fascicles, however, slant 
forward more as they run dorsally and the whole bundle extends 
much farther forward than the deeper coarse-fibered bundle. 
The fascicles break up into diffuse fibers before the pallium is 
reached and many of the fibers may arise from the lentiform 
nucleus itself. It is clear, however, that the greater part of 
these fibers enter into the fiber-layer in which the lateral thick- 
ened border of the pallial cell-layer is imbedded. Moreover, the 
greater part of this bundle is related to the pallial thickening. 
In sagittal sections (fig. 51) fascicles from the superficial 
bundle are traced directly up to the pallial thickening through the 
rostral part of the striatum, and also around the rostral end of 
the striatum through the cell-free zone between the striatum and 
the pyriform lobe. It is interesting to note in sagittal sections 
that medullated fibers enter the pallium and the ventricular 
ridge only in the rostral part (half or more) of each. The bundles 
which rise from the crus into the core of the ventricular ridge 
lose their myelin or disperse so that they can not be traced far- 
ther as fascicles. 
In Chrysemys marginata the ventricular ridge is smaller than 
in Cistudo and does not extend as far forward. The pallila 
