CIRCULATORY APPARATUS OF THE NEMERTBEA. 29 
with the blood-lacunez, or with the exterior. Perhaps they are 
genital spaces. 
4, Valencinia longirostris, Quatref. Figs. 13—16, 
41, 45—47, 50—55, 63, 67. 
The vascular system of Valencinia longirostris resem- 
bles in the head that of Carinoma Armandi, consisting of 
longitudinal lacunze which coalesce into two, when passing 
through the cerebral ring. But for the rest its principal traits 
are also common to all Schizonemertea and Polia. There 
is a median dorsal vessel, which lies in the cesophageal 
region in the proboscidian sheath, and behind it between the 
proboscidian sheath and the intestine. It communicates with 
the lacunze above the inferior brain-commissure and it leaves 
the proboscidian sheath towards the hindmost part of the 
cesophageal region. This region is characterised by two pecu- 
liarities, (1) the whole cesophagus is surrounded by lacune with 
the exception of that portion which lies close to the probos- 
cidian sheath, and (2), this region is the seat of the nephridial 
system. Behind this region two lacune are still visible at the 
sides of the proboscidian sheath, above the foremost half of the 
intestinal tract. Beneath the intestine we find two vessels, so 
that on a transverse section we see five blood-canals, of which 
three have muscular walls and two not. These five blood- 
spaces are united together by transverse vessels. The hind- 
most half of the intestinal region only shows three vessels, the 
lacunz next to the proboscidian sheath having disappeared. 
Here, too, transverse vessels are present. All the transverse 
vessels lie above the diverticula of the intestine. The commu- 
nication of the three longitudinal vessels takes place in the 
tail before the anal commissure of the nerve-trunks and both 
lie above the rectum. 
A series of transverse sections of Valencinia, when 
examined from head to tail, shows in the tip of the snout (in 
my specimen in the ninth section) the beginning of the circular 
muscular layer in the shape of a small curve with its convexity 
