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Show 1904.] ox THE MARIXE FAUXA OP ZAXZIBAR. 287 4. The Marine Fauna of Zanzibar and British East Africa, from Collections made by Cyril Crossland in the Years 1901 and 1902.-The Polychseta. Part III.* With which is incorporated the Account of Stanley Gardiner's Collection made in the Maldive Archipelago- in the Year 1899. By CYRIL CROSSLAND, B.A., B.Sc, F.Z.S., the Gatty Laboratory, St. Andrews. [ Received Decemher 15, 1903.] (Plates XX.-XXII.f and Text-figures 43-G6.) Genus EUXICE. The species fall into the following groups, of which A contains the greater part of the genus :- A. Generalised species with tentacles of moderate length, jaws of normal form and constitution, gills well developed in the adult, and setae of the usual kinds. a. Gills continue to hind end of the body. 1. Gills begin about feet 3 to 8, complex but small in proportion to size of body. a. Quadripartite prostomium, gills of up to 30 filaments, and characteristic seta?... E. aphroditois, p. 288. b. Bitid prostomium, gills of about 8 filaments, and seta? of quite general form . E. grubei, p. 288. 2. Gills begin between feet 15 and 20, attain to from 4 to 10 filaments anteriorly but are simpler posteriorly. Setae of general form E. afra, p. 289. B. Gills occur only on the anterior third of the body. 1. Begin about 6th to 9th feet. Body-form characteristic E. coccinea, p. 297. 15. Forming tubes of characteristic structure and material. Otherwise very like members of group A. 1. Compound setae with sword-shaped articulated pieces anteriorly, sickle-shaped posteriorly ... E. tubifex, p. 303. 2. All compound seta? of the latter form E.floridaua & E. tibiana, E. conglomerate § & E. gunneri (= amphihelite, &c). (These are the remaining species of the group.) C. With long tentacles, large gills beginning before the 10th foot, three-hooked acicular seta-, and markedly asymmetrical jaws. a. Head nearly as broad as the rest of the body, tentacles deeply annul at ed, jaws strong and chitinous. 1. Gills confined to anterior part of the body E. murrayi, p. 310. 2. Gills continued to near anus E. antennata, p. 312. * For Part I., see P. Z. S. 1903, vol. i. p. 169; Part II., 1903, vol. ii. p. 129. t For explanation of the Plates, see p. 330. X It is not suggested that this*, grouping is necessarily of more than temporary utility, but it is certain that in a natural system the larger groups cannot be separated by one character alone, as has hitherto been attempted. Reasons for laying less emphasis upon characters employed for the major divisions by earlier workers are given among the notes on variation of the species described below. § These three species are from Elders' 'Florida Anneliden,' 1887. E. conglomerate is very near to E. tubifex, and is distinguished from all other Eunicids by its compound setaj. |