124 AMPHITRITE SCYLLA. 



eminence probably associated with tube-formation. No eyes are visible in the preparation 

 behind the cephalic collar. 



The body has 120 — 150 segments, and is characterised by its great proportional 

 length and slenderness posteriorly, as well as by its pale cream-colour, here and there 

 enlivened by the blood-vessels and the brownish-red specks posteriorly. The enlarged 

 anterior end has, further, a close series of transverse ridges which have a minutely 

 tessellated appearance from isolated glandular masses arranged transversely. These 

 glands have, besides the granules, clear refracting cells and globules. The separation 

 of the longitudinal dorsal muscular fibres in this region also increases its tessellated 

 aspect. Behind the bristled region the body gradually narrows, and ends in a slender 

 tail with a terminal anus surrounded by marginal papillas. The dorsal surface is convex, 

 the ventral flattened anteriorly and grooved posteriorly. The glandular shields or 

 plates in front are about twelve in number, with a few (three or four) additional 

 small median processes. Behind the region of the shields is a median groove with a 

 prominent ridge on each side. At first lateral, these ridges gradually pass to the 

 mid-ventral line, forming posteriorly a raised belt with a median fissure, then widen 

 a little toward the tail, where the papilla? for the hooks occur in the line of each 

 moniliform ridge, and gradually diminish as the tip is reached. 



Whilst the segments in front have several narrow rings dorsally — giving a finely 

 ribbed aspect to the surface— the narrow posterior region has only the segment-junction 

 separating each smooth segment. The Mediterranean forms appear to be similar in 

 colour to those from the Channel Islands, viz., yellowish-grey. 



Behind the lower lip is apparently a segment with a narrow ventral shield. The 

 next bears the first, and larger, pair of branchiae, each springing from a short stalk 

 and rapidly giving off four main divisions, which split up, after a brief course, 

 into a sub-dichotomously divided tuft with comparatively short terminal branches, 

 the whole forming a dense arbuscle. The second, and smaller, pair is on the next 

 segment and has a similar structure. Occasionally a specimen has three branchia3 

 on one side and two on the other, the third being a small independent stem behind 

 the second. 



Yentralward of the second branchial stalk is a small conical papilla which represents 

 the first setigerous process, though it has no bristles. The next setigerous process has a 

 well-developed tuft of bristles, which are pale, translucent, rather brittle, and in two 

 groups, the longer forms (Plate CXXVa, fig. 2) have long, straight, deeply inserted 

 shafts, which are nearly cylindrical to the commencement of the wings from which they 

 taper to a delicate point. The wings have a characteristic expansion at the base, are 

 narrow distally, and show no serrations. The shorter bristles (Plate CXXVa, fig. 2 a), 

 have peculiarly curved, tapering, serrated tips without distinct wings. Whilst the two 

 setigerous processes behind the branchiae remain isolated and simple, the third presents 

 two processes, viz., the setigerous, and an an tero -ventral papilla, and these continue in 

 the six subsequent feet, the following (from the tenth) setigerous processes, which are 

 somewhat conical, though antero-posteriorly flattened, remaining simple, and the first 

 (tenth) of the (posterior) series having a small papilla below it, at the end of the hook- 

 row. There are twenty pairs of bristle-tufts. The glandular cushions between the 



