122 AMPHITRITE SCYLLA. 



vessels passing from the ventral vessel to the intestine. In the anterior region the 

 dorsal vessel is represented by a perienteric sinus, and this anteriorly opens into a free 

 dorsal contractile heart with a cardiac body. 



Ssolowiew (1899), in his " Terebellids of the White Sea," 1 makes Amphitrite johnstoni 

 fall under Amphitrite brunnea of Stimpson, as also does Marenzeller. 



In the col]ection in the British Museum, Terebella constrictor, according to Malmgren, 

 is T. debilis, = figiilns, = Johnstoni, but the title is on several bottles containing other forms, 

 such as Nicolea, Leprea and Amphitrite scylla. 



6. Amphitrite scylla, Savigny, 1820. Plate CXIII, fig, 2— body; Plate CXXVa, 



figs. 2 — 2 c — bristles and hooks. 



Specific Characters . — Cephalic collar forms a small rim posteriorly, and passes to 

 join the edge of the supra-oral arch. Tentacles numerous, of a pale cream colour. Front 

 edge ends in a prominent spout-shaped arch over the mouth. Lower lip formed by a 

 transverse fold, and within it is a small tongue-like eminence. Body proportionally long 

 and slender, segments 115 — 150, pale cream-coloured enlivened by blood-vessels, and the 

 brownish-red specks posteriorly. The enlarged anterior region has a close series of 

 transverse ridges minutely tessellated from isolated glandular masses. The anus has 

 marginal papillae. Scutes occupy about twelve segments in front with several narrow 

 rings ; the posterior region is marked only by the segment-junctions. Branchiae two pairs, 

 the first and larger pair on the second segment. Each springs from a short stem, which 

 rapidly gives off four main divisions, splitting up into a dense arbuscle with short 

 terminal branches. The second pair is on the next segment. Occasionally a specimen 

 has three branchiae on one side and two on the other, the third being a small independent 

 stem behind the second. Setigerous processes twenty pairs (Von Marenzeller gives seven- 

 teen to nineteen), and in addition a small conical papilla under the second branchia, and 

 conspicuous papillae on segments 6 — 13. The longer bristles have winged tips with a 

 characteristic expansion at the base, and are narrow distally. The shorter bristles have 

 peculiarly curved tapering tips without distinct wings. Hooks commence at the third 

 setigerous process, the first being distinguished by the large size of the main fang and 

 the comparatively small size and oblique nature of the base. By-and-by they form a 

 double row and become typical, the great fang being proportionally smaller, the base less 

 elongated, and the lower edge more convex. In a double row from segment 11, in a 

 single row posteriorly. Body in front of a dull reddish colour, becoming paler behind the 

 anterior region and ventrally ; posteriorly of a pale straw or almost whitish hue marked 

 by the dull grey contents of the intestine. The branchiae, which have tapered tips, are 

 bright red, and are in constant movement with the tentacles when the animal is removed 

 from its tube. The tentacles are pale yellow (straw colour), the tips being more opaque. 

 By flattening out at any part of their length they can attach themselves to the surface of 

 the glass. Some specimens have brownish-red pigment-specks toward the posterior end; 

 others are dull orange anteriorly, pale and translucent posteriorly. Inhabits tunnels in 



fissures of rocks. 



1 ' Ann. Musee Zool. St. Petersb./ p. 202. 



