BY JAS. P. HILL. 23 



111 the iier^e fibre layer, lielow 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 j)rotoplasmic 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 lacunae 

 between the ramifying fibres composing the fibrous la3''er. 



Roots : In this sjoecies 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 foui-, the latter number being the 

 usual one. In one series five roots arose from the collar cord, but 

 I was unal:»le 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 l)lood vessels, and continuous at the 

 one end with the limiting membrane of the dorsal cord, at the 

 t)ther with the limiting meml^rane of the epidermis.' Internal to 

 this is a thin fil^re 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 



