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Show 640 MR. E. A. SMITH ON LAND AND FRESHWATER [Nov. 7 with nodules, but much smaller than the sutural series. It remarkable-looking shell, and probably peculiar to the lake. 26. PHYSA NYASANA, Smith. Hab. Karonga, west shore but towards the northern end of Lake Nyasa (R. Crawshay). The original specimens (described P. Z. S. 1877, p. 717, pi. lxxv. figs. 16, 17) were obtained at the southern part of the lake. 27. PHYSA KARONGENSIS. (Plate LIX. fig. 15.) Testa ovata, angusta, perforata, pallide fuscescens ; anfractus celeriter crescentes, convexi, infra suturam plus minus mareginati, lineis incrementi sculpti, ultiwrus oblique spira brevis, obtusa ; apertura angusta, elongata, longit. paulo superans; columella contorta, reflexa; labrum tenue, intus leviter incrassatum. Longit. 7f millim., diam. 5| ; apertura 5| longa, 2| lata. Hab. Karonga. This species is narrower than P. nyasana, has the spire more elevated, the last whorl obliquely descending and the aperture consequently shorter. This is the third species now known from Nyasa. 28. PLANORBIS (PLANORBULA) ALEXANDRINA, var. Hab. Karonga, Lake Nyasa. This is the first record of the genus from the lake. The single specimen is a link between those from Tanganyika (figured by me P. Z. S. 1881, pi. xxxiv. figs. 30-30 b) and the typical form from Egypt. M. Bourguignat (Ann. Sci. Nat. Zool. vol. x. 1890, p. 23) has considered this variety a distinct species under the name of Planorbula tanganikana. 29. UNIO NYASSAENSIS, Lea. (Plate LIX. figs. 16, 17.) Hab. Angoni-Land, south end of lake Nyasa (A. Whyte). This species is very variable in form and sculpture and offers a fine field for the manufacture of so-called species. Lea described three forms of it under as many names, and M. Bourguignat1 has given a name to a variety which was figured by me in the Society's Proceedings, 1881, pi. xxxiv. fig. 34. 30. UNIO (METAPTERA) JOHNSTONI. (Plate LIX. figs. 18-20.) Testa compressa, transversa, elongata, antice nasuta, acuminata, ad marginem dorsalem sursum acute alata, tenuis, pallida, epidermide dilute virescente postice obscure induta, versus umhones margaritacea, incequivalvis, valde incequilaterdlis, utrinque angustissime hians ; valvce incrementi tenuibus sculptae, supra umbones tenuiter corrugatce margo dorsi incurvatus, ventralis late excurvatus, posticus alam dorsalem et extremitatem posteriorem valde sinuatus ; 1 Bull. Soc. malacol. France, 1889, vol. vi. p. 38. |