I'vEPOKT ON THE ANNELIDA. 
3(35 
The specimeiiis seem to be considerably longer than Prof, Grube’s, the larger 
measuring about 30 mm., with a breadth anteriorly of 4 mm. exclusive of the bristles. 
The segments are also more numerous. 
To the general description of Grube may be appended the structure of the bristles. 
The jointed superior bristles of this form show a peculiarity which has not been 
mentioned by the original describer, viz., that the upper part of each segment is slightly 
dilated superiorly (PI. XXIIIa. fig. 4), especially toward the tip of the bristle. Hansen^ 
indicates a similar condition in his Trophonia hirsuta from the North Atlantic. 
The hooks, again, are slender at the tip, many indeed tapering to a fine point, which 
is pale and striated. The superior also show a slight enlargement at the commencement 
of the translucent extremity. The range in regard to the variation of the tip is indicated 
by the figures in PI. XXIIIa. figs. 5 and 6, the former being one of the lower, the latter 
one of the upper forms. Some of the posterior hooks are even more pointed than in 
fig. 6. Parasitic Infusoria are common on these structures. 
The female specimens show masses of dull brown ova anteriorly, and the male pale sperm- 
masses. The former are easily recognised by the coloration given to the body by the ova. 
The body is somewhat sparsely covered with conical papillse, which in some cases are 
so long as almost to be filiform. No sand-particles or other adventitious structures adhere 
to this form. 
The fine mud in the intestine consisted chiefly of sj)onge-spicules and Diatoms. 
The absence of sand-grains from the skin renders sections of this species comparatively 
simple.. Externally is a dense layer of hyaline chitinous cuticle, which appears to be 
almost of uniform thickness. The same layer covers the long papillse. The hypoderm 
is not much developed except at the bases of the latter, a thin granular layer occurring 
under the former, from which processes pass into the papillae. The circular muscular 
coat is well marked, and apparently continuous. The longitudinal dorsal muscles form 
expanded plates extending from the upper insertions of the oblique to the dorsal median 
line. Their fasciculi do not show any special arrangement. The longitudinal ventral 
cover a smaller area, bounded internally by the oblique muscles and externally by the 
circular coat. The oblique are somewhat strong muscles which meet below the nerve- 
trunks, as in the typical form {Troi^honia ^^lumosa, 0. F. Muller). 
The nerve-cords are separate in the intervals between the ganglia. 
In the anterior third the alimentary tube presents two characters, apparently from 
folds of both regions being included in the sections. The small firm tubes are apparently 
oesophageal, the inner surface being frilled by folds of the dense granular glandular lining, 
while externally is a thin coat of circular muscular fibres. One of these sections invariably 
shows two large folds projecting from the ventral curve. The larger sections pertain to 
the stomachal region of the gut, and have a thick lining of columnar epithelium internally. 
* Den Norske Norclhavs-Exped., Tab. vii. fig. 8. 
