BY JAS. P. HILL. 
23 
In the nerve fibre layer, below the cellular part of the cord, 
nuclei are found, with small oval non-staining cell bodies which 
are produced at either end into fibre-like processes. Clear oval 
spaces also occur in the fibrous layer, but I have not been able to 
convince myself that these form continuous tubes, and they never 
possess any protoplasmic remains in their interior such as Spengel 
describes for the processes passing into the fibrous layer from the 
giant ganglion cells. These spaces appear to be simply lacuna? 
between the ramifying fibres composing the fibrous layer. 
Roots : In this species the most anterior " root " may arise from 
the anterior region, i.e., in front of the middle point of the collar 
cord, contrary to Spengel's statement that the roots always spring 
from its middle or posterior end. Generally, however, the first 
root is situated about the middle region of the cord. The roots 
vary in number from one to four, the latter number being the 
usual one. In one series five roots arose from the collar cord, but 
I was unable to find the dorsal point of union of the fifth with 
the epidermis. As in the described species, the roots vary greatly 
in direction; sometimes they pass straight between the collar cord 
and the epidermis, but generally they take an oblique course, 
forwards or backwards, to their point of union with the epidermis. 
In one series the first two roots fused with each other midway 
between the collar cord and epidermis, while in another series 
two of the roots arose from the collar cord by a short common 
stem. Each root consists as in the described species of an outer 
limiting membrane carrying blood vessels, and continuous at the 
one end with the limiting membrane of the dorsal cord, at the 
other with the limiting membrane of the epidermis. Internal to 
this is a thin fibre layer continuous ventrally with the nerve fibre 
layer of the collar cord. The interior of the root presents a 
varying appearance at different parts; in some sections, and 
especially in those of the first root, a distinct central cavity may 
exist limited by a delicate membrane from which processes radiate 
outwards. These processes apparently belong to cells, the nuclei 
of which are situated just internal to the fibrous layer, the whole 
structure recalling the appearance of the stalked cells radiating 
