AMPHITRITE GIGANTEA. 115 



Synonyms. 



1808. Amphiro gigantea, Montagu. MS. Vol. Linn. Soc., pi. xx, fig. 2. 

 1818. Terebella „ idem. Trans. Linn. Soc, vol. xii, p. 341, Tab. xi. 

 1843-53. „ „ Chenu. Illust. Conch., ll e livr., pi. iv, fig. 2. 



1845. „ „ idem. Bibl. Conch., 2 e ser., t. i, p. 265, pi. xxii. 



1851. „ „ Grrube. Fam. Annel., p. 81. 



1865. ,, Edwardsi, De Quatrefages. Annel., t. ii, p. 354, pi. xix, fig. 1. 



gigantea, idem. Ibid., p. 355. 



„ Johnston. Cat. Worms Brit. Mus., p. 237. 

 1867. „ „ Parfitt. Trans. Dev. Assoc. Sc, p. 32 (sep. c). 



1870. „ „ Grube. Archiv f. Naturges., p. 323. 



1894. Amphitrite Edwardsi, De St. Joseph. Ann. Sc. nat., 7 e ser., t. xvii, p. 186, pi. vii, figs. 207, 208, 



pi. viii, figs. 209—223. 

 1909. ,, „ Fauvel. Ibid., 9 e ser., t. x, p. 209. 



1915. „ „ Allen. Journ. M. B. A., vol. x, p. 633. 



1917. ,, „ Hessle. Zool. Bidr. Uppsala, Bd. v, p. 184. 



Habitat. — In the Zostera banks near the mouth of Salcombe Harbour, with Lepidas- 

 thenia argus as a commensal (Allen). 



Abroad it has been found on the shores of France by De Quatrefages at St. Vaast ; 

 at and near Dinard (De St. Joseph), accompanied by Lepidonotus squamatus as a 

 commensal. It is curious that this Polynoid has not hitherto been found as a commensal 

 in Britain. 



The cephalic region resembles that of A. cirrata though the dorsal lamella for the 

 tentacles appears to be fuller, especially the lateral fold on each side of the lower lip, 

 these being prominent in the large examples. The tentacles form a huge mass, coiling 

 and stretching in life in every direction. 



The body is comparatively large, stretching from 6 to 15 inches or thereabout, 

 enlarged anteriorly and tapering gently posteriorly to the crenate or slightly papillose 

 anus. The skin of the rounded dorsum varies in the preparations, some being compara- 

 tively smooth except for the longitudinal bands of the dorsal muscles, others being 

 tessellated like Scalibregma, and though modified, the same tendency is noticeable in 

 the smoother posterior extremity. The number of segments ranges from 100 to 160. 

 There are eleven ventral scutes, the first being the largest, the last scute being followed 

 by a narrower median glandular belt, which by-and-by diminishes as the ventral groove 

 becomes more pronounced, though toward the tip of the tail it again becomes indistinct. 

 The second, third and fourth segments have in each a free lamella laterally at the anterior 

 border, probably in connection with the functions of the branchise. A diaphragm between 

 the fourth and fifth segments divides the thoracic region into two unequal portions, 

 and it presents two dorsal and two ventral sacs, which De St. Joseph associates with 

 the propulsion forward of the ccelomic fluid. In the posterior region diaphragms occur 

 from the second backward to the tail. Nine pairs of segmental organs anteriorly are 

 described by De St. Joseph. 



The branchise form three dense arbuscles on each side on the second, third and 

 fourth segments. Each has a stout pedicle, which by-and-by splits up into several 



