182 Otkdn'm Fabricn. 



rather narrower than the following ; the anterior with a pro- 

 jecting semioval process on the dorsal aspect, and marked 

 with two round black eyes ? placed towards the sides ; 

 branchial tentacula one third the length of the body? straw 

 colour, unspotted, in two dense tufts originating in the sides 

 of the head, each tuft consisting of three main stalks, which 

 are ciliated with numerous filiform straight filaments, ser- 

 rulate with very short processes on their inner aspects ; 

 mouth between the tufts ; intestine straight, nearly equal 

 throughout; the anus terminal; space between the intestine 

 and sides mottled, transparent. 



This, although not hitherto enumerated among our natives, 

 is certainly the most common species of its family on our 

 coast. It lives in a narrow cylindrical tube, about twice its 

 own length, placed in an erect attitude at the roots of the 

 lesser Fuci. The tube is constructed of fine mud cemented 

 by a glutinous secretion, and lined within by a thin glutinous 

 skin ; and if the worm is removed, and left in clean sea water, 

 it will, after a short interval, be found to have enveloped its 

 body with a similar pellicle. The motions of the tenant in 

 the tube are very lively : it withdraws on the slightest 

 agitation of the water ; and, after its terror has subsided, it 

 again pushes the feathery tentacula from beyond the aper- 

 ture, and expands them in a wide circle, keeping them very 

 steadily at rest: but, when extracted from the tube, it lies 

 very helpless. The tentacula are then stretched forwards, 

 and generally held so approximated that they form a brush, 

 like a hair pencil, on the head, having, however, the apices of 

 the filaments always recurved or hooked. Sometimes the two 

 tufts are a little separated even in this state ; but, from the 

 number and closeness of the filaments, the division of each 

 tuft into three ciliated branches cannot be detected, unless 

 they are lightly compressed between thin plates of glass. 



There are several remarkable peculiarities in this species. 

 The fewness of its segments, the same in number as in cater- 

 pillars, the presence of eyes, or at least eyelike specks, on 

 the first segment, and on the caudal one (for this is not an 

 accidental, but a constant, character), the form of the head, 

 with the peculiar formation of the branchiae, are all characters 

 which separate it from Sabella [VI. 405.], and mark it as the 

 type of a distinct genus. This, accordingly, Blainville has 

 established under the name of Fabriciff, which is, unfor- 

 tunately, preoccupied in botany, and is commemorative of the 

 celebrated entomologist. I have consequently thought myself 

 justified in adopting another; and, in selecting the Christian 

 name (Otho) of the natural historian of Greenland, I adopt 



