114 AMPHITRITE GIGANTEA. 



view three teeth above the main fang, which is long and sharp. The posterior border 

 is convex and a marked heel occurs as it joins the base. The curve below the main 

 fang has a median process, and beyond it is an abrupt bend, whilst the anterior process 

 or prow is rounded and blunt. Striae pass from the small teeth on the crown along the 

 posterior part of the neck. 



The posterior hooks (Plate CXXV, fig. 6 b) are smaller and more compact. 



This species further differs from A. cirrata in the position of the papilla at the 

 anterior setigerous processes, and in the absence of the adjoining flap at the dorsal end of 

 the rows of hooks. 



No tube accompanies it, but as the intestine is filled with whitish mud containing 

 a few sponge-spicules, minute Foraminifera and Radiolarians, many fragments of silex 

 and crustacean hairs, it is probable that the tube is likewise of the same nature. 



Reproduction. — The ccelom had numerous small ova, so that the example is a female. 



The hook of this form has certain resemblances to Amphitrlte Birulai, Ssolowiew, 1 

 and if his drawing is faulty it might prove to be a variety. 



Southern (1914) states that the hooks are in two rows in segments 11 — 20, but 

 in the others in a single row. He thinks it closely approaches A. variabilis of Risso. 

 An examination of an example kindly sent by Mr. Southern shows that it is a small one, 

 with the characters less boldly marked than in larger forms. 



Wollebsek's 2 figure of the hook, whilst evidently pertaining to A. affinis, has 

 certain differences, such as the size of the process on the anterior outline (below the main 

 fang), and the depth of the blunt prow. 



This species was also placed by Hessle under his genus Neoamphitrite. 



4. Amphitritb gigantea, Montagu, 1818. Plate CXX, fig. 11 — branchia; Plate CXXV a, 



figs. 10 — 10 b — bristles and hook. 



Specific Characters. — Cephalic region as in A. cirrata, though the lateral processes 

 of the tentacular plate seem to be larger proportionally. Two statocysts near the 

 cephalic ganglia. Body more than a foot long, 15 — 18 mm. in diameter in the anterior 

 region, and tapered posteriorly to a crenate or papillose anus. The number of segments 

 ranges from 100 to 160. Seventeen pairs of bristle-tufts occur anteriorly, the tips 

 having wings and a translucent, serrated blade beyond them. The shaft dilates a little 

 about the commencement of the wings. The hooks have a longer base than in A. cirrata, 

 five or six teeth above the main fang, and the outlines on each side of the process on 

 the anterior border are more distinctly concave. Nine pairs of segmental organs 

 anteriorly (De St. Joseph). The body is of a uniform chamois (buff) colour, the setigerous 

 processes and hook-rows being paler. The branchiae are deep red and the tentacles 

 orange, whilst the dorsum is of a greyish blue anteriorly. Tube a gallery in the 

 sandy mud. 



1 < Ann. Mus. St. Petersb./ t. iv, p. 198, Taf. xii, fig. 10, 1899. 



2 Op. cit., pi. xxxiv, fig. 6. 



