64 : J. B. JOHNSTON, 
better to await their confirmation before entering into an extended 
discussion of HALLER’s results. I wish to acknowledge my indeb- 
tedness to the officers of the Michigan Fish Commission for the 
greater part of the material upon which this work has been done. 
Valuable suggestions in the use of the GOLGI stain were received 
from Dr. STRONG at the Wood’s Holl Biological Laboratory in the 
summer of 1896. I owe an especial debt to Professor REIGHARD 
for his careful oversight and criticism of my work, for which I wish 
to express my hearty thanks. 
II. Gross Anatomy. 
The following description is brief and is intended merely to 
make the description of the minute structure clear. It differs from 
the description and figures of GORONOWITSCH only in minor points, 
due chiefly to the difference in species used, but adds to that de- 
scription some details regarding surface characters which are related 
to internal structures. 
A. Hind Brain. 
a) Medulla. 
Photograph 1 shows the entire brain from the left side, the 
left half of the choroid roof of the IV ventricle having been removed. 
The length of the several divisions of the brain is about as follows: 
hind brain (measuring from the commissura infima Halleri) 30 mm, 
mid brain and ‘tween brain 10 mm, fore brain and olfactory lobe 
15 mm. The nearly straight ventral contour of the medulla shows 
a gentle curve upward at its cephalic end. The dorsal border of 
its lateral wall rises gradually from bebind forward and presents an 
abrupt elevation at its cephalic end, the lobus lineae lateralis, se- 
parated by a depression from the lateral lobe of the cerebellum. 
In dorsal view (Phots. 5, 6, 7) the medulla is seen to widen very 
slowly in front of the calamus being laterally compressed by the 
enormous vagus nerves. Farther forward it widens more rapidly 
and then more slowly up to the cerebellum. This widening is due 
in part to the increase in volume of the lateral and dorso-lateral 
zones and in part to the enlarging of the cavity of the fourth ventricle. 
In the lateral view (Phot. 1), the first root of the XII nerve is 
seen to be a little caudal to the middle of the region occupied 
by the roots of the X. The right vagus nerve is photographed in 
position. It rises slightly dorsad as it passes backward, and grows 
