CELL MASSES IN THE FOREBRAIN 397 
ger’s figure 121 the term epistriatum is applied to an entirely 
different body in the turtle, the dorsal ventricular ridge of the 
present paper. In figure 125a, which also represents the turtle, 
this ridge is called mesostriatum and the term epistriatum is 
applied to the pallial thickening. Since the structure to which 
the term epistriatum was first applied does not appear as a special 
body or ridge in the turtle brain and since the author of the term 
uses it for at least three different bodies in the reptilian brain, 
the term will not be used in the present paper. The use of purely 
descriptive terms will help to avoid confusion. 
In the dissected brain or in the model from which the hippo- 
campal formation has been removed (figs. 4, 10) it is seen that the 
dorsal ventricular ridge bends down into the temporal pole. 
Here it enters into close relations with the amygdaloid complex 
which must be discussed later. 
FORMATIO OLFACTORIA 
The formatio olfactoria is that portion of the forebrain which 
receives fila olfactoria and contains mitral cells and glomeruli. 
It forms the rostral part of the olfactory bulb and extends farther 
caudally on the dorsal than on the ventral surface. Thus the 
peduncular constriction is placed obliquely, as is evident in figures 
3and5. The bulb in its rostral part is nearly triangular in cross 
section (fig. 30). The olfactory nerve divides into distinct 
ventral and dorsal roots. The ventral spreads upon the dorsal 
surface of the bulb and enters the brain farther rostrally than 
does the dorsal root. The ventral root spreads over somewhat 
more than the lower half of the medial and lateral walls (fig. 30) 
and the rostral surface. The dorsal root continues over the bulb 
as a high ridge and spreads out in the dorsal wall in its caudal 
part. At its greatest extent, near the peduncle, this root ex- 
tends half way down on the medial and lateral surfaces. The 
areas in which bundles of fila olfactoria are evident are shown in 
figures 28, 29, 30. It is certain, however, that many fila extend 
either in small bundles or singly some distance beyond these 
limits before ending in relation with neurones of the formatio 
olfactoria. 
