The Prosobranchs of Lake Tanganyika

Abstract

WHEN Sir Richard Burton discovered Lake Tanganyika in 1858 his companion, Speke, collected a number of shells from the shores. These proved to be Prosobranchs of types hitherto unknown in fresh water. Later investigations, notably those of the three Tanganyika expeditions, the first two under the leadership of J. E. S. Moore1 and the third under that of W. A. Cun-nington2, revealed in fuller detail the remarkable nature of the fauna with its great number of endemic species of fish, Crustacea, sponges and, above all, prosobranch Gastropoda. Cunnington lists 84 species of Gastropoda of which 76 are endemic. The majority, 72 species, are Prosobranchia and of these 68 are endemic. Moreover 58 species have a heavy, frequently ornamented, shell, in appearance much more like marine than freshwater species. Moore, elaborating a suggestion made originally by Giinther3, regarded these, and the other endemic species, as a relict fauna, the descendants of a diverse collection of marine species which lived in this region when Tanganyika was, as he maintained, an arm of the Indian Ocean. He described them as "halolimnic"species.