98 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
these, occur scattered over the dorsal surface of the brain, and a group 
of them lies around the root of the fourteenth nerve (XIV). 
(2) At the posterior lateral border of the brain there is a group of 
spindle-shaped cells, which extends backward and outward along the root 
of the thirteenth nerve (XIII) as far as the point where the nerve 
pierces the capsule (Plate 2, Figs, 9, 15). These cells do not stain very 
deeply, and do not show very sharply defined cell boundarics, although 
the spindle form can be distinctly seen. Similar cells give rise to the 
fibres that form the fourteenth nerve and pass out to the dorsal sur- 
face of the head. 
(3) Along the internal border of the last group there lies a third very 
peculiar class of cells (Figs. 9, 12). Unlike those of the two preceding 
classes, the cells of this class have a very definite cell boundary. They 
are comparatively few in number, and are narrowly pear-shaped with the 
process extending toward the centre of the brain. In preparations 
stained to best advantage for other structures these cells are so deeply 
stained that only in a few cases can the nucleus of the cell be scen at all. 
The cell process also stains so deeply that it appears in strong contrast 
with the other fibres. 
(4) In the same transverse section as the last, but nearer the median 
plane, is another group of pear-shaped cells (Figs. 9, 11). These are 
larger and proportionately broader than the last, and stain very differ- 
ently from them. In iron-heematoxylin the cytoplasm does not become 
blue, but takes on a brownish color. Its structure is almost homogene- 
ous excepting an irregular network of a few coarse fibres which usually 
centres about the nucleus and does not extend throughout the body 
of the cell, The processes of these cells also go toward the centre of 
the brain. 
(5) At the side of the brain beneath the nerve of the anterior eye 
there lies a group of cells which seem to have no direct connection with 
the brain except that of being enclosed in the brain capsule. The cells 
are rather large and spherical, and send their processes out along the 
ninth nerve (IX) of the brain toward the commissural ganglion, A few 
of the cells lie scattered along the dorsal side of the ninth nerve, and 
make this group of cells continuous with the group which lies beneath 
the anterior eye, and which we have called the optic ganglion. The cells 
of both groups have the same general appearance (Fig. 19). The cyto- 
plasm presents no special peculiarities. There is no cell membrane and 
the limits of the cell are very indistinct, because there are very few 
granules at the periphery. Each cell is surrounded by neuroglia fibres 
