440 
THE VOYAGE OF H.M.S. CHALLENGER. 
a much shorter and proportionally broader hook at the tip. Both have the duct 
perforating the tip. The shaft of the new species is also much shorter and thicker than 
the Norwegian, indeed it approaches in this respect the Canadian form. The duct or 
groove seems to be due to a splitting of the dorsal margin of the hook, and it appears 
sometimes to be incomplete at the extremity. The bristles are decidedly longer in the 
new form and the tip more attenuate. The wings in both species are narrow. 
The hooks of the two species, as might be expected, are very closely allied, yet in the 
general outline of each there is sufhcient to distinguish them. The hook in the new 
form (PI. XXVIIa. fig. 15) is more elongated from the crown to the anterior inferior 
angle than in the Norwegian (PI. XXVIIa. fig. 16), some of the uncini, indeed, showing- 
four teeth above the supra-mucronal one instead of three as in the figure. The curvature 
of both base and dorsum is also diagnostic ; and the flexures at and above tbe anterior 
inferior process (or mucro) are dissimilar. The respective figures best demonstrate dis- 
tinctions which are difficult to explain concisely. 
Posteriorly forty- two or forty -three segments occur between the last bristle-bundle 
and the anus, so that the region is comparatively long and tapered, though apparently 
shorter than in Melinna cristata. The anus appears to be a simple wide funnel, and no 
cirri are present in the specimen. 
The example is somewhat soft and the hypoderm rather incomplete. It seems, how- 
ever, to have considerable depth ventrally. The circular coat is moderately strong. The 
longitudinal ventral muscles are massive and convex inferiorly, while the dorsal are 
somewhat extended. The nerve-cords agree in position with those of Amphicteis. 
Melinna pacijica, n. sp. (PL XL VIII. fig. 6 ; PI. XXVIIa. fig. 17). 
Habitat. — Trawled at Station 246 (nearly in Mid Pacific, in a line between Japan 
and San Francisco), July 2, 1875 ; lat. 36° 10' N., long. 178° 0' E.; depth, 2050 
fathoms; bottom temperature 35°‘l, surface temperature 73°'0; sea-bottom, Globigerina 
ooze. 
The specimens were all enclosed in their tubes, and thus were imperfectly preserved, 
the spirit not having penetrated sufficiently before softening occurred. The size is variable, 
the longest ranging from 45 to 50 mm., with a diameter at the thick anterior region of 
fully 3 mm., exclusive of the bristles. 
The contrast between the head of this form and that of the Norwegian Melinna 
cristata is striking, from the great development of the large, club-shaped, and elongated 
tentacles, which, when in situ in the tube, are folded in front of the snout and 
beneath the branchiae. They are grooved, and, in the preparation, crenate ; and 
evidently are capable of great extension. Their bases, as in the common form, are 
