CIRCULATORY APPARATUS OF THE NEMERTEA. 21 
that of the vascular system (see figs. 4, 24).! These excretory 
ducts lie above the lateral nerves. The epithelial layer and 
the hyaline basal layer clothe the whole duct. The epithelial 
layer passes gradually into that of the skin. The hyaline basal 
layer coalesces with the basal membrane of the skin, which 
deviates outwards, and the layer of circular fibres passes into 
that same layer which lies within the basal membrane. The 
whole is remarkable as bearing a very primitive character. 
The skin shows in the living animal a hardly perceptible cup- 
shaped deepening. In a transverse section this is seen to 
correspond with the outer infundibulum of the duct. 
Behind the nephridial region I have followed the vascular 
system much further. The vessels in the intestinal region lie 
sometimes beneath, sometimes above the level of the lateral nerves 
(figs. 21, 22), are large and wide, and their wall again consists of 
the three layers already described. Here, too, I searched in 
vain for an exterior layer of longitudinal fibres to the vessel. 
I have not had occasion to observe the connection of the 
two vessels in the posterior extremity of the animal. 
3. Carinoma Armandi (MclInt.), Oud.; figs. 5, 28—37, 
56—61, 72—75. 
Of this species the vascular system, neglecting a few smaller 
vessels, consists of four large lacune in the head, which com- 
municate in the tip of the snout, and form two lacune in the 
cephalic region, passing into six longitudinal vessels further 
backwards, two of which are situated in the proboscidian 
sheath, terminating blindly behind two others above and out- 
side of the proboscidian sheath, which also terminate blindly 
behind, whilst two others, which extend along the whole length 
1 Inducement to search for the nephridia of Carinella, unknown till to- 
day, and to hope to find a communication with the vascular system, was 
given me when Professor Hubrecht communicated to me that he had met with 
nephridia in two genera closely related to Carinella (the still inedited genus 
Carinina dredged by the “Challenger,” and Valencinia Armandi;, 
MciInt.), and that he had succeeded in finding in the latter the internal and 
direct communication of the nephridium with the vascular system. 
