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Show 1906.] OX MOLLUSKS FROM THE PERSIAN GULF. 7 8 3 5. The Mollusca of the Persian Gulf, Gulf ot Oman, and Arabian Sea, as evidenced mainly through the Collections of Mr. F.AY.Townsend, 1893-1906; with Descriptions of new Species. By J a m e s C o sm o M e l v i l l , M.A., F.L.S., F.Z.S., and R o b e r t S t a n d e n , Assist.-Keeper, Manchester Museum. P a r t II.-PELECYPODA * [Received September 10, 1006.] (Plates LIII.-LYI.+) In this, the second portion of our enumeration, over 420 species are mentioned, and, of these, more than one-sixth, say 76 species, were discovered either by Mr. Townsend or Mr. Alexander Abercrombie, and have been in greater part described by one of the present authors during the past thirteen or fourteen years. These include a considerable number of, mainly, small and abyssal forms, now to be differentiated in the subsequent pages of this paper. In the first part of our Catalogue, a census of 935 species, all Gastropoda, excepting for about 12 or 13 Scaphopoda, wras given. Five or six years having now elapsed since its publication, the number has been continually increased owing to the products of several further dredgings on the part of Mr. Townsend having-been now fully wrorked out, and the results-at all events, so far as the new species are concerned-published in a series of articles, references to which will be given below. With these additions, the number of Mollusca as yet detected in this area is as follows:- Cephalopoda .............. 2 1 Gastropoda .............. 1175 Scaphopoda .............. 15 Pelecypoda . ............. 426 Total . . . . 1618 species. This, wTe believe, already slightly eclipses the sum of the rich Mediterranean Fauna, to which it bears a considerable generic analogy, though so widely differing specifically. And, likewise, compared with Erythraean forms, it will be found, numerically, to surpass them in even still greater a degree, for hardly more than a thousand species have so far been catalogued as natives of the Red Sea, rich though that Sea be both in variety and prolific occurrence of individuals. It must also be borne in mind that both the Mediterranean and Erythraean Seas have been far more assiduously explored than the region under discussion, and any further discoveries # For Part I. see P. Z. S. 1901 (vol. ii.), p. 327. t For explanation of the Plates, see p. 848. t In Cephalopoda, only the genera Nautilus, Argonauta, and Sjpirula have been considered here. |