166 NEREIDiE. 



prickless proboscis ; and the serratures of the jaws are likewise fainter 

 than in any other I have examined. As the specimen of H. longis- 

 sima is not in a good condition, some allowance will be made, should 

 the outline given of the posterior foot be found not wholly exact ; but 

 I am confident that the general contour and proportions are accu- 

 rately expressed. 



Before I examined this worm, I had mistaken it for a species of 

 Phyllodocey which it more resembles in size and general aspect than 

 a HeteronereiSi and it is obviously a transition species, proving the 

 affinity of these two genera. The foliaceous lamellae of the feet are 

 quite similar in structure to the branchial leaflets of the PhyllodocCy 

 and, from the manner in which they are veined, are evidently also 

 branchial in their function. 



Obs. A large species, with much of the habit of a Phyllodoce. 

 Post-occipital segment not longer than the second ; tentacular cirri 

 short, not so long as the breadth of the segment. Segments very 

 numerous ; the feet of the anterior with three rather long papillary 

 and equal lobes, the dorsal cirrus not reaching much beyond the 

 apex of the dorsal lobe. 



4. H. margaritacea, jaws with five to six denticulations, plain at the 

 apex ; post-occipital segment twice as long as the second, with ten- 

 tacular cirri about equal to its diameter ; feet lobulated, the lobes 

 oblique, the dorsal without a crest, and overtopped by its cirrus ; 

 foliaceous lamella one only, cordate ; inferior cirrus with a papilla 

 at its base. Length 4". Plate XV. fig. 3. 



Nereis margaritacea, Johnston in Ann. Nat. Hist. iii. 294. pi. 6. f. 3. 

 Hab. The coralline region. Amongst the rocks at Milton, rare, 

 Montagu. Coast of Berwickshire, rare. 



Desc. Body about 4 inches long, rounded dorsally, and flattened 

 on the belly, of a uniform mother-of-pearl colour, iridescent, the feet 

 tinted with a dusky pale green. Head corneous, brown, subqua- 

 drangular. Eyes four, very distinct. Antennae and palpi similar to 

 those of N. viridis, nor is there any material difl'erence in the pro- 

 boscis, but the jaws are armed with only five or six denticulations, 

 and the point is longer and smooth. Tentacular cirri subequal, 

 reaching to the posterior margin of the post-occipital segment, which 

 is twice as broad as the following. Segments rather narrow ; the 

 anterior with small feet, but they become gradually larger as we 

 reckon backwards, attaining their maximum of development below 

 the middle, whence they again begin to get less. Superior cirrus 

 longer than the branchial lobule ; the inferior cirrus of the anterior 

 feet simple, that of the more developed feet with a lobe and short 

 filament at its base. Bristles in two considerable brushes, colour- 

 less, compound, the point long and setaceous. Spines darker. 



The species appears to be allied to the Nereilepas variabilis of 

 Oersted, but they are distinct. 



