CELL MASSES IN THE FOREBRAIN 423 
bears the characteristics of the lateral thick border. In other 
words, it may be stated that the body recognized in the gross 
brain as a pallial thickening occupies the rostral end of the 
general pallial area and extends caudad as a gradually diminish- 
ing lateral thick border. The pallial thickening is characterized 
by the presence of a well-developed peripheral layer of cells and 
this suggests a special functional significance for this body. 
The pallial thickening last described is the most highly special- 
ized part of the general pallium and is farthest removed from 
the brain stem. The temporal portion of the pallium, adjacent 
to the amygdaloid fissure, is the most primitive and simple in 
structure. In the caudal part of the basal surface of the heni- 
sphere, where the temporal and occipital poles may be said to meet, 
the general pallium presents a somewhat more open arrangement 
than in most of the pallium (fig. 46). A larger number of cells 
are placed near the outer surface. From this point rostrad, to- 
ward the amygdaloid eminence, there is the line of transition 
between pallium and hippocampus and an area of pallium in 
which the cells become more and more irregularly scattered as 
one follows the sections forward (figs. 45, 44). At its lateral 
border this pallial area bends inward to become continuous 
with the cell masses in the dorsal ventricular ridge (figs. 11, 12). 
As the sections are followed forward it becomes evident that this 
part of the pallium is related to that basal and caudal part of the 
ventricular ridge whose ventricular surface is covered by the 
large-celled nucleus of the amygdaloid complex (fig. 44). 
In sections which pass through the caudal part of the pyri- 
form lobe and the deeper and broader part of the amygdaloid 
_fissure (fig. 13), the caudo-lateral prolongation of the nucleus of 
the lateral olfactory tract appears in the depth of the fissure. 
Now the general pallial area on the basal surface is bounded 
by the hippocampus medially and by the nucleus of the lateral 
olfactory tract laterally. Internally the pallial cells merge with 
those of the basal lobe of the ventricular ridge. As the sections 
are followed forward the nucleus of the lateral olfactory tract 
increases in size while the hippocampal formation disappears 
from the sections before the tip of the temporal horn of the 
