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Show 1899.] ON LAND-SHELLS FROM BRITISH CENTRAL AFRICA. 579 3. On a Collection of Land-Shells from British Central Africa. By E D G A R A. S M I T H , F.Z.S. [Received April 13, 1899.] (Plates XXXIIL-XXXV.) The collection about to be described was presented to the British Museum by Sir Harry Johnston in 1896 and 1897, and a brief notice of a portion of it has already appeared in his book on 'British Central Africa' (pp. 363, 364). It is of special interest, as very little is known respecting the terrestrial Mollusca of this particular region. The country to the north and east, in German East Africa, has been conchologically explored by many collectors, and a very valuable report upon the fauna has been given by Dr. E. von Martens, in 1897, in a work entitled ' Be-schalte Weichthiere Deutsch-Ost-Afrikas.' Only a very few species, however, had previously been collected in Nyasaland, and reference to these has already been made by the writer in the Society's ' Proceedings ' for 1891, p. 309. Although the present collection contains examples of as man}* as twenty-five new species out of a total of forty-four enumerated, none of them are representatives of new generic types, and the forecast given in the paper referred to has, judging by tbe present collection, proved to be correct in every respect1. The "interesting intermediate links connecting some of the large species of Achatina " have been met with, and a number of new species of other groups of Helicidoe " have been found." In working out this collection much difficulty was experienced in determining the Achatince. The species appear to grade one into the other, and the more examples we have, the greater the trouble becomes. The genus is spread over the greater part of Central and West Africa, as far north as Sene-gambia, and each district seems to produce its special race, a modification of some neighbouring form ; so that the separation of species becomes more and more difficult through the discovery of intermediate links from every fresh locality. The same may be said of the Ennece, and indeed of most of the other groups. The specimens were obtained by Mr. Alexander Whyte, or under his direction, at the following localities :- (1) Nyika Plateau, 7000 feet, towards the north end of Lake Nyasa, on the west side ; (2) Mount Zomba, 6000 feet; (3) Zomba Plateau, 5000 feet; (4) Mount Chiradzulu, 5000 feet; and (5) Malosa, 6000 feet, all to the south of the lake. The Masuku Plateau 6000-7000 feet, where several of the specimens were obtained, is also probably in the same region. 1 The collection also contained a few slugs, including Atoxon tceniatum Sim roth (?) and a species of Veronicella. |
