260 Cc. JUDSON HERRICK 
dorsal division of the tract, though more diffusely arranged fibers 
are freely distributed throughout the lateral wall. 
The rostral end of the hemisphere is least affected by the as- 
cending diencephalic systems, and it is to this relatively unspecial- 
ized part of the olfactory area that the term nucleus olfac- 
torius anterior has been applied. In some animals it is an 
extensive region bordering the olfactory bulb or even extending 
out into it; in others the elaboration of special centers like the 
Fig. 37. Diagrammatic horizontal section through the brain of Amblystoma, 
to illustrate the connections of the ventrolateral nucleus of the cerebral hemi- 
sphere. : 
tuberculum olfactorium has invaded this territory so that but 
little such undifferentiated secondary olfactory tissue remains. 
In urodeles this anterior nucleus is fairly extensive on the 
lateral wall, especially dorsally. 
The ventrolateral area of the urodele hemisphere is dominated 
(except at the rostral end) by the lateral forebrain bundle. This 
contains, in all of the urodele species which I have examined, 
an extensive system of fine unmyelinated fibers which ascend 
from the pars dorsalis thalami, which I first called tractus 
thalamo-corticalis (710, p. 434) and later tractus thalamo-frontalis 
Cig, Dp. 208): 
