375 
of Edinburgh , Session 1876-77. 
outer border of the region, — a few fibres passing downward to 
curve outward at the circular coat of the body-wall. Externally, 
between the latter coat (and a layer of somewhat isolated longitu- 
dinal fibres within it), are the hypoderm and cuticle. In Eunice 
norvegica , L., a similar arrangement occurs in the anterior third, 
and a large median neural canal lies below the cords. The strong 
oblique muscles pass down to the ventral hypoderm. Distinct 
muscular bands also enclose the ventral blood-vessel and nerve 
trunk in a tunnel. A little behind the middle of Eunice Harassii , 
Aud. and Ed., the cords present the same external coverings, only, 
from the great size of the oblique and vertical muscles, they are 
somewhat supported by the latter inferiorly. The same arrange- 
ment occurs in a large male Eunice from the “ Porcupine.” The 
constancy of the muscular tunnel for the nerve-cords and ventral 
blood-vessel is interesting. 
Onupbidid^. — The oblique muscles in both Notliria con- 
chylega, Sars., and Hyalinoecia tubicola , 0. F. Muller, are well 
developed, and not only meet, but slightly cross, in the middle 
line. The nerve-cords lie in the angle of decussation superiorly, 
and have a single neural canal of considerable size towards the 
lower border. Besides the oblique are externally the circular 
muscular coat (which, in H . tubicola , is specially developed in the 
median line), a narrow band of hypoderm, and the dense cuticle. 
Goniadxd^.— -In the anterior region of Goniada maculata, 
(Erst., the powerful oblique muscles sweep from below the bristle- 
bundles on each side, with a slight inclination downward and 
inward, and meet for insertion on each side of the hypodermic 
wedge above the nerves. The latter occupy a somewhat triangular 
area of the hypoderm, and each has a small neural canal toward 
the upper and narrow part. In Eone Nordmanniy Mgrn., the 
nerves are proportionally smaller, and the hypodermic area less. 
Glyceride. — The cords at the anterior third of Glycera 
capitata , (Erst., are large, and occur in a hypodermic region, wedged 
between the great longitudinal ventral muscles, which touch in 
the middle line, so as to form an arch over the nerves. The great 
external circular muscular layer ceases before reaching the nerve- 
area, so that externally the latter has only the hypoderm and the 
specially thickened cuticle. The oblique muscles are very slightly 
VOL. ix. g d 
