126 Wirvıam A. Hınron, 
describes in Cynthia centrosomes which have about the position in 
the cells that these pigment bodies do; but I found no indication 
of centrosomes in Tunica nigra. 
Summary. 
1. The ganglion of Tunica nigra possesses more branches than 
have been described for related forms. Many of these are quite 
small. The larger nerves seem to contain both afferent and efferent 
fibers. The smallest branches seem to supply nearby muscles. 
Some few muscles are evidently supplied rather directly by cells 
lying at the periphery of the ganglion. 
2. The neural gland on the ventral side of the ganglion is in 
places almost fused with the nerve center, but free nerve cells were 
not found among the gland cells. 
3. The duct from the gland to the ciliated funnel was much 
like what has been described by METCALF and many others. 
4. Small, somewhat variable strands were recognized in some 
specimens as rapheal nerves. Another rather thicker mass of nervous 
substance was found ending abruptly in the connective tissue. This 
was on the ventral side near the atrial end and was apparently a 
vestigal structure. Not any of these peripheral nervous structures 
contained nerve cells. 
5 The nerve cells of the ganglion were densely crowded into 
a cortical layer, the central core being composed chiefly of nerve 
fibers. There were a few scattered cells located in the central part 
of this mass of fibers. 
6. A large proportion of the cells of the periphery evidently 
supply muscles. A few cells of the peripheral portion of the ganglion 
and many of the scattered central cells serve apparently for various 
sorts of association. 
In all parts of the ganglion are cells which are apparently 
connective rather than nervous in function. These are usually 
smaller than the nerve cells and have very little cytoplasm. 
7. In the central portions of the ganglion is an intricate mesh- 
work of fibrillae, which in places is seen to be continuons from cell 
to cell and with the fibrillae within the nerve cells. 
8. Tigroid-like substance is found in the nerve cells, some- 
