OIROCULATORY APPARATUS OF THE NEMIERTEA. 65 
ones. From these dorsolateral vessels I often observed delicate 
branches running almost straight to the periphery, above the 
lateral nerves. Never, however, did I succeed in finding a 
piercing of the basal membrane or of the skin. Do they 
terminate blindly ? It is to be hoped that some later observer 
may find the excretory ducts of this nepridial system, for I do 
not doubt but this system of fine canals and dorsolateral vessels 
belongs to a nephridial system. (Compare the nepridial 
system of all Hoplonemertea in which the principal (longi- 
tudinal) canal also always lies more or less above the nerve- 
trunks!) I hesitated to represent the system in my illustration 
(fig. 8) on account of its complicated character. 
In histological structure the nephridial (?) canals do not 
deviate from the transverse vessels of the vascular system 
(figs. 70, 71), even the dorsolateral, and the transversely cut 
connecting points occasionally visible between the transverse 
vessels above the proboscidian sheath, had the same structure 
only they were larger. They all exhibited an outer ring of 
large vesicular cells, round a hyaline basal layer, in which were 
some large granular nuclei, which were not to be distinguished 
from all other nuclei in the gelatinous stroma of the head or of 
the vesicular cells themselves. The nuclei lay in a fine granular 
layer. Are these nuclei blood-corpuscles and is this fine 
granular layer blood-coagulum, or do they both belong to the 
coating of the vessels? This I could not decide. 
The median and the two ventrolateral vessels had between the 
basal layer and the ring of vesicular cells a layer of circular 
muscular fibres. 
In the intestinal region the transverse vessels run over only 
a few of the diverticula. Inthe tail, however, they occur more 
frequently, yet here and there skipping a diverticulum. 
The lateral vessels always lie beneath the nerve-stems, not 
beneath the intestine. 
17. Drepanophorus rubrostriatus, Hubr., fig. 7, 42. 
The vascular system consists of a cephalic loop, running 
above the proboscidian sheath. (Proboscidian sheath and 
5 
