373 
of Edinburgh, Session 1876-77. 
than in Panthalis, and the hypodermic area for the nerve is thus 
increased in depth. Superiorly the arch is completely covered by 
the insertions of the vertical and oblique muscles ; and it is inte- 
resting that the latter do not pierce the former (which occupy the 
middle line), but are attached to the basement -tissue below them, 
on each side of the nerve-area. The cords are almond-shaped in 
transverse section, whereas in S. Mathilda e, Aud. and Ed., they are 
round, and the hypodermic area enclosing them is much more 
expanded inferiorly. 
Nephthydjdje. — In Nephtliys coeca , Fabr., the combined oblique 
and vertical are attached along the entire arch of basement- 
tissue, above the nerve-area. A broad hypodermic belt exists 
above the nerve trunks, and a narrower between them and the 
cuticle. 
Phyllodocid^:. — The nerves in Phyllodoce groenlandica, (Erst., 
are situated within the circular muscular coat, and above 
the insertions of the oblique muscles (which decussate in the 
middle line), as well as such fibres of the vertical muscles as are 
inserted into the basement-tissue of the ventral hypoderm. In 
Eteone picta , De Quatref., and Eulalia viridis , 0. F. Miiller, certain 
fibres of the oblique pass at intervals right over the cords, so as to 
form a continuous band from side to side, and in the former an 
interval between the oblique muscles is indicated. 
In Alciope the cords also lie within the circular muscular layer — 
in the interval between the longitudinal ventral. The oblique pass 
below the cords, but do not appear to meet in the middle line- The 
sole specimen, however, is indifferently preserved for microscopic 
work. 
HEsiONiDiE. — The trunks in Ophiodromus vittatus , Sars., have 
in the anterior region passed below the ventral attachment of 
the oblique muscles to the basement-tissue. A thin stratum of 
longitudinal fibres occurs superiorly, while externally is a thickened 
hypoderm. The nerves seem to be proportionally large. 
Syllidjs. — In Syllis armillaris, 0. F. Muller, the nerve-cords 
are also comparatively large. A considerable depth of the closely 
approximated ventral longitudinal muscles shuts them from 
the very thin hypodermic elements within the thickened cuticle, 
except in the intervals between the ganglia, where there is a 
