POLYCIRRUS AUBANTIACUS. 197 



Reproduction. — A large example from Plymouth on March 11th had small ova in its 

 ccelom. 



Grube (I860), in his original description, gave this form ten pairs of setigerous 

 processes with capillary bristles and commencing on the second segment, but he added 

 that behind them were twenty-one pairs of short bristle- tufts— scarcely distinguishable. 

 The rows of hooks commence on the twenty-first segment and are about seventy-two in 

 number on each side. In his excursion to Trieste he at once observed the distinction 

 between this form and P. medusa. 



In 1864 Claparede made a note on this group, which was brought into prominence 

 first by Milne Edwards in his Report of M. De Quatref ages' observations to the Academy 

 of Science, Paris (on the Aphlebines). In this communication the Swiss author described 

 two forms, viz. Aplilebina hmwiatodes and A. pallida distinguished by coloration, the 

 structure of the hooks, and, as he thought, by the number of the bristle-tufts. 



In 1875 Panceri gave a short description with figures of this species, the figure of 

 the anterior region and the tentacles representing the luminosity, though the purple is 

 perhaps too deep. He locates the phosphorescent elements in unicellular glands in the 

 tentacles and along the body. 



Considerable variety seems to occur in the commencement of the tori ; thus Langer- 

 hans (1880) gives a range from the fifth to the ninth, the latter referring to a specimen 

 with seventy segments. The segments with dorsal bristles range from twelve to thirty- 

 seven, also following mainly the size. The number with stout bristles (Stiitzbursten) is 

 apparently always thirteen. He (1880) gives a recognisable figure of the anterior hooks, 

 though the posterior outline is rather long in proportion to the posterior projection, and he 

 has not noticed the slight eminence on the anterior outline just below the throat — a process 

 better marked in the posterior hooks. It occurred at Madeira chiefly in the deeper water 

 and in fish-baskets. He gives twelve segments to the thoracic region and forty-four in all, 

 and three pairs of segmental organs, whilst the bristles are from twelve to nineteen pairs. 



Parasites. — Brumpt 1 (1897) found a curious Crustacean (Saccopsis Alleni) parasitic 

 on this species at Plymouth, and which is closely allied to Saccopsis Terebellidis, Levinsen. 

 Caullery and Mesnil 2 also describe a remarkable form, Xenocoeloma brumpti, which is 

 attached to another species of Poly cirrus (P. arenivorus), but has a communication with 

 the coelome of the annelid, and a process from the intestine exists at its base. The 

 authors consider that Brumpt's form has a similar connection. 



3. Polycjerus caltendrum, Claparede, 1868. Plate CXXVII, figs. 8 and Sa — hooks. 



Specific Characters. — Cephalic region and tentacles as in P. aurantiacus, and show 

 the same colour and bluish or violet phosphorescence. Tentaculiferous surface often 

 elegantly pigmented. Body terebelliform, 3 — 10 cm. long, with a breadth of 2 — 4 mm. 

 Setigerous segments 34 — 70, and non-setigerous 28 — 75. Ventral scutes eight pairs, 

 besides the large anterior median one. Six pairs of orange segmental organs in the six 



1 f Comp. Rend. Ac. Sc. Paris/ June 21st, 1897. 



2 ' Corapt. rend./ t. clxi, p. 642, 1915. 



