149 



No. XXIV. 



Nereis pelagica. 



Desc. Body from 4 to 6, or, when fully exteuded, even 8 inches hi 

 length, semicylindrical, of the thickness of a goose-quill, tapered 

 towards the tail, of a brown or flesh colour more or less lustrous, 

 with metallic or olive-green reflexions, par- 

 ticularly near the head, and on the anterior 

 margins or sides of the rings. Head trian- 

 gulate (No. XXIV.), obtusely pointed in 

 front. Eyes four. The superior tentacular 

 cirri reach to the margin of the fourth ring, 

 and are longer by a third than the second 

 pair, which again are nearly twice the length 

 of the inferior pairs. Mouth with a large 

 proboscis armedwith two strong jaws, around 

 which are placed, on as many swellings, 

 six distinct patches of small black prickles, 

 the side patches larger than the others ; 

 two still smaller patches are situated just under the projecting 

 lobe of the head, while at the very base of the proboscis we find 

 a band of similar prickles, some larger than others, arranged in 

 several irregular series. Jaws falcate, dark browu except at the 

 base, with ten serratures. First ring twice as large as the following, 

 scored with faint whitish lines or sometimes spotted ; and oblique 



No. XXV. — Nereis pelagica. 



lines of the same kind may be seen, with a magnifier, on the sides of 

 the other segments, of which, in a large specimen, there were 1 23, 

 smooth, excepting that across the front margin of a few of the ante- 

 rior segments a line of minute granules is very often visible. Feet 

 (No. XXV.) nearly all alike, the cirri short, the terminal or branchial 

 lobules conical, nearly equal on the anterior feet, but towards the mid- 

 dle of the body the superior becomes larger and more prominent than 

 either of the others ; setigerous tubercles small, the bristles of the 

 superior fewer and more slender thaii those of the inferior, all of them 

 two-jointed, the terminal piece obliquely set, setaceous, smooth, liable 

 to be broken off; the bristles are as usual acicular and falcate. Spines 

 one to each bundle of bristles, acute, dark brown. Anal segment 

 white, and terminated with two short styles. 



Obs. This is the commonest species of its genus. It is always 

 more or less tinged with green, on the front especially ; and the red 

 vessel that runs down the dorso-medial line is always very conspi- 

 cuous. The proboscis is a beautifully armed organ ; the basal half 

 is encircled with numerous prickles in several irregular series, and 



