Gaily Marine Laboratory, St. Awlrewft. 105 



M. elisahetlice), then turns backward to the edge of the denti- 

 culated membrane of the fourth setigerous segment. The 

 latter, tlie lower lip, and the lateral folds thus form a kind 

 of base or sheath for all the parts in front. The transverse 

 and free fold just alluded to has about a dozen denticulations 

 of nearly equal size on its free or anterior edge. 



The body is somewhat clavate, broad at the branchial 

 region, and gently tapering to the slender posterior extreuiitj^ 

 which is characterised amongst the Ampharetidpe by its 

 great length, no less than about fifty segments occurring 

 in it. The anus is terminal, comparatively large for the 

 size of the region, and in the only example in which the 

 part is apparently complete a few short papillee occurred 

 on the edge. A.bove and beneath the anus is a vertical slit 

 with the lateral edge projecting on each side. The dorsal 

 surface of the body is rounded and smooth, whilst the 

 ventral surface is marked anteriorly, as far as the fourteenth 

 bristle-bundle, by the glandular thickenings in each segment ; 

 thereafter a median groove is continued to the slender 

 region near the tip of the tail. 



The first three bristle-bundles are small, and form a 

 slightly oblique row in the preparations along the edge of 

 the flap between the mouth and the denticulated border on the 

 dorsum of the fourth bristled segment; these have no evident 

 setigerous process, since they are immersed in the tissues 

 of the region. The following fifteen pairs have, when fully 

 developed, a prominent and somewhat conical setigerous 

 process, from which the long pale golden bristles project 

 either transversely or in a slightly backward direction. The 

 bristles have long finely striated shafts and slightly curved 

 and winged tips, which taper to a fine point. A shorter 

 series occurs amongst the foregoing, their finely tapered 

 ti])s falling short of the longer by a considerable interval. 



-Between the basal region of the branchiae on each side and 

 the denticulated margin of the dorsal collar is a powerful 

 hook which, in the preparations, is gejierally conspicuous, 

 the point being directed backward and downward. It has 

 a broad flattened base and shaft, the latter widening as it 

 proceeds upward from the base to about half its length, 

 then narrows distally, the tip forming a sharp hook which 

 curves to the front. Along the dorsal or convex edge of the 

 curve a considerable thickening of the brittle chitinous 

 tissue occurs, and this part is perforated by a canal con- 

 taining granular contents, and in connection with a gland, 

 also granular, at the side of the shaft. The canal opens on 

 the convex side of the organ a little short of the tip. The 



