MELINNA CRISTATA. 85 



bluntly-rounded process with (in some) a notch in the centre. In extrusion of the 

 tentacles there is a flattened lamella, from the anterior edge of which the somewhat 

 clavate tentacles project. The tentacular lobe is separated by a deep dorsal groove from 

 the next segment, the groove passing laterally downward to the mouth in front of the 

 posterior lip. Two basal processes arise from the third segment, each of which soon splits 

 into two anterior and two posterior rather long tapering branchiae, the larger being the 

 inner of the anterior pair on each side, the two outer being considerably less than the 

 inner posterior. The posterior lip forms a lamella with a free anterior edge which curves 

 upward on each side to form a prominent collar at the angle (thus differing from M. 

 elisabethse), then it turns backward to the edge of the denticulated membrane of the fourth 

 setigerous segment. The latter, the 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 extremity, which is characterised amongst the Ampharetidae 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 papillae occurred on the edge. Above or 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 thickening in each segment ; 

 thereafter a median groove is continued to the slender region near the tip of the tail. 



Hessle 1 found two glands at the sides of the hooks on the dorsal surface behind the 

 branchiae. He regards these hooks as representing a reduced fourth segment. The 

 glands have a muscular investment and their duct communicates with the hollow hook. 



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, but the tips are occasionally modified, 

 probably by friction, so that they are bent nearly at right angles and split, so as to 

 resemble hooks. 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 (Plate CXXV, fig. 1) 

 have long, finely striated shafts, and slightly curved and winged tips which taper to a 

 delicate point. A shorter series occurs amongst the foregoing, their finely-tapered tips 

 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 (Plate CXXV, fig. 1 a), which in the preparations 

 is generally conspicuous, the point being directed backward and downward. It has a 

 broad flattened base and shaft ; the latter widens 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 containing 



1 Op. cit., pp. 53 and 54. 



