SABELLARIA ALVEOLATA. 31 



round the margin of the lower lip. The mucous ribs or folds sloped obliquely from the 

 median ventral ridge and met at an angle in the mid-dorsal line. He evaginated the 

 caudal tube, which showed a spiral or oblique arrangement of ribs internally with a 

 ventral ridge apparently in connection with the expulsion of the excreta. The inner 

 lining was infested by parasitic worms (Nematodes ?) 



Eye-spots occur in young forms (Fig. 140), after the disappearance of the central 

 cirrus, at the V-shaped origin of the ridge anteriorly. The cirri at each side of 

 the building organ appear to be proportionally larger in the very young forms 

 (Arnold Watson). 



Arnold Watson observes " that the position of the nephridiopores for the emission of 

 ova is on the posterior face of the uncinigerous lobes, whilst the pores for the emission 

 of sperms are on the dorsum just behind the base of the branchial processes." " The 

 pores of the head-kidney are in the angle formed by the first pair of branchia3 with 

 the body." 



Rejjroductlon. — Specimens from Naples (probably procured in summer) had ova of 



Fig. 1-40.— Sketch of the folds and eye-spots of a young example of Sabellaria alveolata. oc, eye-spots ; 

 r., ridge ; op.l., opercular lobes. After an outline by Arnold Watson. 



considerable size in the ccelomic space. Lo Bianco (1893 and 1909) states that artificial 

 fecundation was carried out at Naples between September and June. Arnold Watson 

 mentions that the ova are cream-coloured, or, at any rate, much less tinged with pink, 

 and smaller than those of S. spinnlosa. 



Tubes. — Considerable masses of the tubes (Plate CXVIII, fig. 2) are found in the 

 estuaries of many English rivers, composed either of fine or coarse sand-particles some- 

 times dotted over with pure white Forammifera, as if sparsely studded with pearls. 

 The coarse tube figured by Chenu (1843-53) might pass for that of Tetreres murata, 

 Allen, if indeed it is not that form. 



An interesting variation in the form of the tube was procured by Arnold Watson at 

 St. Mawes, in which the aperture of each tube had a broad flat projection like a shield over 

 it, and composed of the same coarse grains of sand as the rest of the structure. He 

 considers that this addition may have some relation to the intensity of the light in the 

 situation chosen by the annelid, though it is possible that protection from certain enemies 

 may also be a reason. In watching the building operations of a young example, Mr. 

 Watson observed the grains of sand rotated and held in place by the " palps," the lips by 

 their sucker-action meantime covering them with cement. After a number of grains had 



