REPORT ON THE ANNELIDA. 
145 
(intermediate in position) have somewhat elongate tips of a single segment. Both 
shaft and tip are very translucent, the former showing, towards its distal end, a few 
indications of the ordinary spinous rows. The extremities have a jDeculiar curve 
(PI. XIIIa. fig. 13) at the base of the terminal hook, the anterior edge especially 
being thin and translucent. 
The ventral cirrus is long and tapering, the tip reaching considerably beyond the 
setigerous lobe. The enlargement usually connected with the ventral papilla is present, 
but no papilla is visible. Two ciliated pads occur on the upper border of the foot, and 
a process beneath the branchia. The foot is further characterised by the foliaceous 
cutaneous expansions on each side inferiorly. The specimen is a female, and has 
numerous large greyish ova posteriorly. 
This form presents certain special characteristics in the structure of its 
body-wall. Thus, the longitudinal dorsal muscles meet in the middle line with- 
out much diminution, while their outer border bends inward and is once or twice 
spirally rolled. The ventral longitudinal muscles are compact and somewhat 
rounded in transverse section, the outer margin being pinnate and spirally rolled 
inward. Instead of the meagre margin of hypoderm seen in the former species, 
the ventral area is crown-shaped, broader, and with rounded margins superiorly — 
where the oblique muscles are attached, slightly contracted inferiorly — where the thin 
layer of h 5 ^poderm trends under the ventral longitudinal muscles. The area is 
thus large and deep, and the somewhat ovoid nerve-cord (in section) occupies the outer 
and inferior region, a distinct neural canal, moreover, occurring on the inner side of 
the nerve, about its middle. The rounded form of the ventral longitudinal muscles 
is evidently due to the strength and shortness of the othque muscles which arch 
tightly over them superiorly. The cuticle is thick inferiorly, but the hypoderm forms 
a comparatively thin coat. 
This form, therefore, approaches Psammolyce in the arrangement of its 
nerve -area. 
Sigalion, Milne-Edwards. 
Sigalion hushii, MT. (PI. XXII. fig. 1). 
Sigalion busMi, M‘I., Trans. Zool. Soc. LoncL, vol. ix. pt. 7, p. 391, pi. Ixx. fig. 14. 
Sthenelais dendrolepis (Clap.), MT., Trans. Roy. Soc. Edin., vol. xxv. p. 409, pi. xii. fig. 12, and 
pi. XV. figs. 4, 5. 
Habitat. — Dredged, along with many other Annelids, at Station 75 (off Fayal, 
Azores), July 2, 1873 ; lat. 38° 38' N., long. 28° 28' W. ; depth, 450 fathoms ; surface 
temperature, 70°‘0 ; sea-bottom, volcanic mud. The distribution of this species, wnich 
is very well characterised, is therefore wide, ranging from North Unst, Shetland, in 90 
fathoms, to the Azores. 
(zool. CHALL. exp. — PART XXXIV. — 1885.) 
LI 19 
