310 LAGISCA EXTENUATA. 



terminal feet. At the tail the tips of the attenuate ventral bristles become much 

 elongated, some, however, maintaining the typical outline. 



The dorsal cirri spring from the posterior border of the foot, and in those feet 

 without scales a well-marked papilla, the homologue of the scale-peduncle, occurs at the 

 inner border of the basal process of the cirri. They are somewhat slender, and have 

 numerous and slightly tapered cilia with a bulbous tip. The cilia are shorter interiorly 

 above the base, and again dis tally, and they cease about the middle of the filiform tip. 

 Posteriorly the cirri become longer and more slender, and the cilia more attenuate. 

 The caudal cirri are also slender. The long first ventral cirrus is stout, with a distinct 

 enlargement below the tip, which is much less filiform than the dorsal. The cilia, which 

 are considerably shorter and more uniform in length than those on the dorsal cirri, 

 extend from the base beyond the middle of the terminal slender region. They are 

 slender processes with a bulbous tip. 



Loxosomm occur at the bases of the bristles and algee with other forms on them. 

 In Grube's original description of Polynoe extenuata 1 the scales are entered as 

 smooth at the edge, and with minute warts. The inferior bristles are a fourth longer 

 than the upper. Colour brownish grey above, bluish iridescent beneath. Elytra 

 caducous. There is nothing to give certainty. 



Baron de St. Joseph (1888) found one in the tube of Serpula vermicularis, but it 

 may have simply crept there for temporary shelter. He is of opinion it is closely allied 

 to Lagisca floccosa. 



Hornell (1891) describes apparently the same form from the Liverpool district, 

 though his figure of the dorsal bristles is rather indefinite. Its relation to Evarne impar, 

 to which he refers, is less marked than to Lagisca floccosa. The figure of the scale given 

 by this author differs from those procured by the ' Porcupine. 5 



This form would seem to be nearly allied to Grube's P. extenuata as described 

 by Marenzeller in his ' Adriatic Annelida.' 2 He does not give the minute details nor 

 describe the special condition in the tips of the upper bristles, which are longer in his 

 figure and more distinctly bifid than in the British examples. On the whole the latter 

 would seem to be a well-marked variety, in which the secondary process of the ventral 

 bristles was less developed. 



De St. Joseph (1878) , 3 after Langerhans, would make Lagisca rarispina and L. 

 propinqua, Malmgren, varieties of this species — a view which the preceding descriptions 

 and figures will sufficiently criticise. He had the advantage of the specimens in the 

 Parisian Museum in identifying Lepidonotus Leachii and L. dumetosus, both of De 

 Quatrefages, with Lagisca extenuata. 



i ' Actin., Echin., u. Wiir./ p. 86, 1840. 

 2 Op. oit., 1898 ; p. 238. 



