CELL MASSES IN THE FOREBRAIN 417 
core of the ventricular ridge where they are somewhat more 
compactly arranged than in the pallium. The section passes 
through the caudal part of the amygdaloid fissure. It is readily 
seen that the ventricular ridge corresponds to the external groove 
and that the fissure is a true fold of the brain wall. Examina- 
tion of the relations of all parts of the dorsal ridge gives the im- 
pression that the ridge is an infolding of the brain wall from 
this region and that it has. pushed forward well toward the 
rostral end of the hemisphere. Its cell layers come into continu- 
ity with those of the pallium here in the amygdaloid fissure and 
with no other nucleus whatever. They are sharply distinguished 
from those of the caudate and lenticular nuclei and from the 
pyriform lobe and are usually separated from these by cell-free 
zones (figs. 11 to 22). In its rostral part the ridge is sharply 
separated from all other cell masses and projects freely into the 
ventricle. 
Ina transverse section taken at the level of the stria medullaris 
the cells in this ridge present the arrangement seen in figure 16. 
All around the ventricular surface are a great number of large 
and small clusters of cells. Some of these clusters are large, 
rounded and have a definite outline. Others are very irregular 
and their outlying cells mingle with the scattered cells between 
the clusters. The individual cells of the clusters do not differ 
materially in size from those of the adjacent general pallium but 
are conspicuously larger than those in any other part of the same 
section. In the lower part of the ridge, adjacent to the middle 
ventricular groove, there is a tendency for the cells to be closely 
aggregated in a large area without special clusters. 
The core or central part of the ridge is largely filled by fibers 
among which are scattered cells. These cells are smaller than 
those of the clusters. The ventral part of this area is encroached 
upon by the lentiform nucleus and by the main body of fibers 
entering or leaving the ridge (figs. 15 to 22). The dorsal part of 
the central area of the ridge contains a larger number of cells 
almost evenly scattered. Many of these cells approach in size 
those of the clusters. This part has almost the appearance of 
an independent cell-mass and for convenience may be called the 
