270 Proceedings of Boyal Society of EdmhurgTi. [sess. 
review of the whole group are the undifferentiated condition of 
the ctenidial and osphradial ganglia and the chiastoneure condition 
of the pleuro-visceral connectives. 
I have, in conclusion, to express my obligation to Professor 
M‘Intosh and the authorities of the South Kensington Museum 
for the material for this investigation ; and to Professor Ewart, 
who afforded me every facility for carrying out the work in the 
Zoological Laboratory of the University of Edinburgh. 
EXPLANATION OF PLATE. 
Fig. 1. Dolabella ruinphii, pa, parapodia ; m, mantle ; s, exhalent sipho. 
Fig. 2. Diagrammatic cross section of Dolabella rumphii, pa, parapodia ; 
sh, shell ; m, mantle ; f, fold ; gl, mantle gland ; ct, gill ; f, fold ; h.g. , 
hypobrauchial gland. 
Fig. 3. Dolabella rumphii, right parapodium removed, a, attachment of 
mantle to left parapodium ; an, anus ; f, fold ; g, gap in fold ; g.f., genital 
furrow ; g.o., genital opening ; h.g., hypobrauchial gland ; m, mantle ; pa, 
left parapodium. 
Fig. 4. Transverse section of mantle, sh, shell ; f, fold ; gl, mantle glands. 
Fig. 5. Section through mantle and osphradium, c, glandular protuberance 
of mantle ; ct.n., ctenidial nerve; m, mantle; os.g., osphradial ganglion; 
S.I., lid closing osphradial pit ; os.n., nerve to osphradium ; sh, shell. 
