The brain of Acipenser. 143 
The fibres which end in this nucleus in the region of the prae- 
optic recess come from the cephalic direction and I believe that 
they are fibres from the olfactory lobe. In that part of the nucleus 
cephalad from the anterior commissure it has been impossible to 
determine the source of the afferent fibres, but the cells are favorably 
situated for receiving olfactory tract fibres. I consider the nucleus 
as a whole as belonging to the area olfactoria and at least the caudal 
part of it as representing the nucleus taeniae of higher forms. 
In the extreme dorso-cephalic part of the fore brain is a group 
of cells which perhaps constitutes a nucleus postolfactorius dorsalis. 
Its cells which have been impregnated in only one series are shown 
in Phot. 74. They bear some resemblance to the cells in the ventral 
and lateral nuclei, but their neurites were not impregnated. It is 
quite possible that these should be grouped with the cells next to 
be described, the cortical cells. 
3) Cortex. 
On the lateral surface of the fore brain are found a few cells 
measuring 12—18 by 16—40 u, with two or more dendrites usually 
disposed parallel with the external surface. Owing to the formation 
of precipitates in the superficial parts of the brain, these cells have 
been difficult to study. The precipitate is especially troublesome in 
the work of photographing the cells. I present one rather poor 
photograph (66) which shows one of these cells with the neurite directed 
ventrad. The cell body is not more than 50 u beneath the lateral 
surface, which appears at the left in the photograph, and the den- 
drites and neurite are parallel with the surface. The neurites of these 
cells arise from one of the dendrites, and are relatively coarse fibres 
with very regular varicosities, which are directed toward the anterior 
commissure. I have not had the fortune to trace these fibres through 
their whole course. Similar fibres which I have found in the anterior 
commissure, in a superficial position, pass over the lateral surface 
of the fore brain and enter the epistriatum near its dorso-lateral 
angle. Either before or after entering the epistriatum, the fibres 
divide into several very fine branches which run for a long distance 
in the epistriatum between its layers of cells The manner of 
ending of these fibres is very characteristic. I think there is no 
doubt that they belong to the cells mentioned. 
Although these cells are few in number, I have found them in 
different preparations in almost all parts of the lateral surface of 
