74 A. C. OUDEMANS. 
munication between the vascular system and the proboscidian 
sheath, I must distinctly negative it as far as my own experience 
goes. I therefore wish to suggest another hypothesis, viz. that 
the two blindly terminating vessels in the proboscidian sheath of 
the Palzo-type, as well as that portion of the median vessel 
which lies in the proboscidian sheath in the Schizo- and Hoplo- 
type, and “‘ the membranaceous sacs” (Hubrecht) in Drepano- 
phorus, are intended for purposes of respiration, nutrition, 
and excretion of the fluid contained in the proboscidian 
sheath. 
It is superfluous here to resume all the reasons which have 
led me to this supposition. I beg to refer the reader to what 
has been stated above, where this subject was more extensively 
alluded to. 
LITERATURE OF THE SUBJECT CONTAINING REFERENCES EITHER 
TO THE VASCULAR OR THE Excretory Systems OF THE 
NEMERTEA. 
1. Dette Cutase.—‘ Memoria sulla storia e notomia degli animali senza 
vertebre del regno di Napoli,’ volume ii, p. 408, 1828. 
2. Dretie Cutase.— Descrizione e notomia degli animali invertebrati delle 
Sicilia citeriore osservati vivi negli anni 1823-30, vol. iii, p- 128. 
3. DuegEs.—Apercu de quelques observations nouvelles sur les Planaires 
et plusieurs genres voisins,”’ ‘ Ann. Sc. Nat.,’ xxi, 1830. 
4. Jounston.—* Miscellanea Zoologica,” ‘Magazine of Zoology and 
Botany,’ i, 1837. 
5. Raruxe.—* Beitriige zur vergleichenden Anatomie und Physiologie,” 
Neueste Schriften der Naturf. Ges. zu Danzig, iii, 1842. 
6. BuancHarp.—“ Mémoire sur un animal appartenant au sous-embranche- 
ment des vers. (Le genre Malacobdelle de Blainville),” ‘ Ann. Se. 
Nat.’ (3)—* Zool.,” iv, 1845. 
7. De QuatreracEs.—‘ Etudes sur les types inférieurs de l’ébranchement 
des Annelés, mémoire sur la famille des Némertiens,” ‘ Ann. Se. Nat. 
(3)—* Zool.,” vi, 1846. 
8. Brancuarp.— Recherches sur l’organisation des Vers.,” chap. v et chap. 
ix, ‘Ann. Se. Nat.’ (3)—“ Zool.,” viii, 1847. 
9. BuancHarp.— Recherches sur l’organisation des Vers.,” chap. xii, ‘ Ann. 
Se. Nat.’ (3)—* Zool.,” xii, 1849. 
