THE FOREBRAIN OF THE ALLIGATOR 359 
others, it cannot be regarded as true neopallium, but rather 
represents a process of differentiation in that direction. 
Johnston (16a) by a series of experiments on the turtle brain 
has reached the conclusion that there is some degree of cortical 
localization in the general pallium of that reptile. The writer 
at present has not sufficient data to determine whether or not 
there is any localization pattern in Alligator mississippiensis. 
Centers of the diencephalon 
The diencephalon may be divided into the three usual divisions 
(1) the epithalamus; (2) the thalmus; (8) the hypothalamus. 
It is not the purpose of this report to go into the question of 
nuclear localization in these regions nor to attempt to describe 
the character of the cell groups. There has not been sufficient 
work done to justify such an attempt. Only a few of the more 
outstanding facts of especial interest in connection with the 
discussion of the forebrain will be mentioned. 
At the end of his 1913 paper, DeLange has given a series of 
outlines of the diencephalon of the alligator in which the posi- 
tions of the various nuclei and their topographic relations to the 
various fiber tracts are indicated. These have been of the great- 
est help. 
Epithalamus. The part of the epithalamus which is_par- 
ticularly concerned with the reception of olfactory impulses 
is the habenula (figs. 11, 12, 21). This nucleus lies at the dor- 
sal surface of the diencephalon and projects into the ventricle. 
The stria medullaris brings impulses to this nucleus. It con- 
sists of three smaller nuclei; a medial one of closely packed cells, 
a dorsal and more anterior one which apparently receives part 
of the tractus cortico-habenularis medialis and, lastly, a ventral 
one of larger cells that, farther caudad, connects with the cell 
mass of nucleus magnocellularis. The habenulae of the two 
sides connect with each other by means of the commissura haben- 
ularum (fig. 12). 
Thalamus. There are really three types of nuclei in the thal- 
amus proper: a medial group which connects chiefly with the 
