CIRCULATORY APPARATUS OF THE NEMERTEA. 79 
Fie. 39.—Through the precerebral region. 
Fie. 40.—Through the cesophageal region. Excretory ducts of the nephri- 
dial system, both above and below the nerve-trunks. 
Frc. 41.—Through the intestinal region of Hoplonemertea (excl. Mala- 
cobdella), Schizonemertea, Valenciniide, and Poliide. See 
Figs. 10, 12, 16, and 18. 
Fie. 42.—Through the cesophageal region of Drepanophorus rubro- 
striatus, Hubr., with two membranaceous sacs of the proboscidian sheath, 
and the two only excretory ducts of the nephridial system. 
Figs. 43—51.—Polia curta, Hubr. See Fig. 11. 
Fre. 43.—Through the precerebral region. The foremost lacune do not 
communicate with one another. 
Fic. 44.—Through the cerebral region. Communication between the 
cephalic lacune above the proboscidian sheath. 
Fic. 45.—Ditto. The lacune on the sides of the proboscidian sheath at 
first coalesce beneath the sheath and then divide into three parts, one of which 
lies beneath the sheath. 
Fie. 46.—Ditto. Communication between the cephalic lacune and the 
median vessel in the proboscidian sheath. 
Fic. 47.—Ditto. Communication of all the lacune, which now spread over 
the brain lobes. 
Fic. 48.—Through the postcerebral region. The posterior lobes bathe in 
the lacune. 
Fic. 49.—Ditto. The forward projecting part of the stomodeum bathes in 
the lacune, partly lying above the posterior lobes, which are still visible. 
Fic. 50.—Ditto. The mouth lies in the section. Two lacune, one on 
each side. 
Fic. 51.—Through the cesophageal region. The lacune surround the 
esophagus, except on its dorsal surface. ‘The nephridial system lies in the 
lacuna against its outer border. Two of the excretory ducts are severed by 
the section. 
Figs. 52, 53. —Valencinia longirostris, Quatr. See Fig. 14. 
Fic. 52.—Through the foremost part of the intestine. The csophageal 
lacune are continued into the two lateral (ventral) vessels, and the two lacunse 
on the sides of the proboscidian sheath. (The median vessel here lies beneath 
the sheath.) The five vessels are united by transverse vessels. 
Fic. 53.—Through the precerebral region, in front of the opening of the 
proboscidian sheath. Numerous cephalic lacune. 
Fic. 54.—Through the cerebral region of Lineus sanguineus (Rathke), 
MclInt. (cerebral ring). The abnormal method of communication between the 
cephalic lacune and the median vessel. See Fig. 17. 
