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Show 1903.] ON THE MARINE FAUNA OF ZANZIBAR. 169 2. On the Marine Fauna of Zanzibar and British East Africa, from Collections made by Cyril Crossland in the Years 1901 and 1902.- Polychgeta. Part I. By C y r il C r o s s l a n d , B.A., B.Sc.1 [Received January 15, 1903.] (Plates X V I. & X V I I .2) Introduction. The collections referred to were made under the following circumstances :- Sir Charles Eliot, K.C.M.G., C.B., late Fellow of All Souls College, Oxford, at present H.M. Consul-General at Zanzibar and Commissioner for British East Africa, took me out with him as his private assistant in his researches on Nudibranch Mollusca. I made collections not only of this, but of the other marine groups ; accounts of which, by various specialists, will appear in these ‘ Proceedings ' from time to time. The largest collections are those of the Nudibranchiate Mollusca and Polychrete Annelids, of which groups about 150 species in each are to be described. Sir Charles Eliot has already published one part of the results of his examination of the Nudibranchs (P. Z. S. 1902, vol. ii. p. 62); other papers by various authors will shortly be ready. For the benefit of other possible workers in this region, I may mention that the greater part of my collections was made in two localities, viz. Cliuaka Bay, on the east coast of Zanzibar, and Wasin Harbour, near the Anglo-German boundary on the mainland. The former locality is extremely rich in shore forms, and dredging in 3 fathoms of water at the north side of the mouth of the bay was often very productive. Wasin Harbour averages a depth of 10 fathoms, and here I collected almost entirely by dredging. The bottom is extensively covered by a species of Telesto, the branches of which are overgrown by an encrusting red sponge. Among this a great variety of the smaller Polychgeta and Nudibranchiata are found. My mention of these two localities is of the more importance to future workers because large stretches of the coast are extremely barren. Unfortunately this applies to the two principal towns of East Africa, and especially to Mombasa. A few miles from Zanzibar, e. g. round the islands and sandbanks which surround the harbour, and on one portion of the shore about a mile to the south of the town, at low spring-tide only, are rich collecting-grounds, and near this latter area dredging is profitable, especially at a depth of 5 fathoms. The greatest portion of the Zanzibar channel is, however, extremely barren. More detailed descriptions of the reefs of East Africa, with maps, will be found in my two papers: " On the Coral Reefs of Zanzibar," and " Pemba and British East Africa," in the Proc. Camb. Phil. Soc. vols. xi. & xii. (1902). 1 Communicated by Prof. W. C. M c In to sh , F.Z.S. 2 For explanation of the Plates, see p. 176. |
