138 EUNICE. 



hence surely the reason that the mouth has been furnished with the 

 hard tubercles to the lips ; for, when pulled together and put in con- 

 tact, they must give a firmer gripe and hold than could otherwise be 

 taken. 



The use of the tube is to protect the body from the pressure of 

 the soft mud in which it stands immersed. When the tube is over- 

 set or cast out by the waves or accident, the worm leaves it, and 

 becomes, in its turn, exposed to enemies. To protect itself from 

 these while a new tulbe is being secreted, nature has amply furnished 

 the Sao with a series of bristUng lances on each side. These arms are 

 of exquisite make, very fine and very sharp ; and those of the upper 

 bundle have their points bent and inchued towards those of the 

 lower bundle, which are likewise bent to meet them. Arms like 

 these will inflict wounds on the tiny assailants of the Sao sufficiently 

 painful to repulse them ; and a lethal wound is unnecessary. 



(a) Plymouth Sound, C. Prideaux. 



\b) Scotland, Lieut. Thomas, R.N.* 



2. N. conchylega, the tube flattened, free, formed of agglutinated 

 fragments of shells and gravel : posterior tentacula on a short basal 

 joint. 



Onuphis conchylega, Sars, Beskr. 61. tab. 10. f. 28. Grube, Fain. 



Annel. 44. 

 Sabella compressa, Mont. Test. Brit. 555. Turt. Brit. Faun. 203. 



Penn. Brit. Zool. edit. 1812, iv. 372. 



Hab. The coralline region. 



Desc. Worm scolopendriform, a little narrowed towards each ex- 

 tremity, convex dorsally, more flattened on the ventral surface, and 

 furrowed as usual in the median line ; of a yellowish-brown colour, 

 with faint iridescent lines across in the sutures. Head small, distinct, 

 with two lobe-like palpi, and five greatly, but unequal, elongated 

 tentacula. Eyes two, lateral, placed backwards. Segments nume- 

 rovis, narrow, subequal, with a protuberant foot on each side. The 

 first and second pairs of feet project forwards, like buttresses, on 

 each side of the head, and reach a little beyond its front margin. 

 These feet (No. XXI. fig. a) are armed each with about four strong 

 simple bristles (fig. b) curved slightly at the apex, which is strong 

 and not very acute. The feet which follow protrude laterally, and 

 are armed with an elongated dorsal and ventral cirrus, and with two 

 small brushes of bristles. These bristles are all simple, smooth, 

 slender, but unequal, the linear shaft bent obliquely so as to form a 

 sort of falciform point (fig. b). There is a spine (fig. cl) in each 

 brush, distinguished by its straight figure. There appear to be 

 about fourteen rings thus furnished, when suddenly their character 



* Lieut. Thomas, R.N., has repeatedly seen the worm turn itself in its tube. 

 To do this the head is reverted, and pushed down within the tube, between the 

 wall and the body. The body is drac^ged in the same course, until the reversion 

 is completed, and the head occupies the end that had been occupied by the tail. 



