640 MK. E. A. SMITH ON LA.-N-D AND PRESIIWATEE [NoV. 7 



with nodules, but much smaller than the sutural series. It is a 

 remarkable-looking shell, and probably peculiar to the lake. 



26. Phtsa NYASAifA, Smith. 



Hah. Karonga, west shore but towards the northern end of 

 Lake Nyasa {B. Crawsliay). 



The original specimens (described P. Z. S. 1877, p. 717, pi. Ixxv. 

 figs. 16, 17) were obtained at the southern part of the lake. 



27. Physa KAROifGENsis. (Plate LIX. fig. 15.) 



Testa ovata, angiista, perforata, iHillide fuscescens ; anfracfvs 3|, 

 eeleritcr crescentes, convexi, infra suturam phis minus distincte 

 marginati, lineis incrementi scidj^ti, ultiir^us oblique descendens ; 

 spira brevis, obtusa ; apertxira angnsta, elongaia, longit. totiits j 

 panic siiperans ; columella conior'ta, refle.m ; labrum ienue, 

 intus leviter incrassatn m . 

 Lovgit. 7f millim., diam. 5| ; apertura 5| longa, 2| lata. 

 Hah. Karonga. 



This species is narrower than P. nyaMina, 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. PiANOEBis (Pla^^obbtjia) alexa'n^deina, var. 



Hah. 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 h) 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 

 Planorlmla tanganihana. 



29. Unio jS^tassaensis, Lea. (Plate LIX. figs. 16, 17.) 

 Hah. Angoni-Land, south end of lake Nyasa {A. Wligte). 



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. Bourguignat ' has 

 given a name to a variety which was figured by me in the Society's 

 Proceedings, 1881, pi. xxxiv. fig. 34, 



30. Unio (Metapteka) JomfSTowi. (Plate LIX, figs. 18-20.) 

 Testa compressa, transversa, elongata, antice nasnta., piostice 



aamiinata, ad marginem dorsalem sursum acute alata, tenuis, 

 pallida, epidermide dilute virescente postice obscure radiata 

 induta, versus umbones margaritacea, inceqnivalvis, valde 

 incequilateralis, utrinque angxistissime hians ; valvcc striis 

 incrementi tenuihus sculptcv, sxipra umbones tenuiter corrugatce ; 

 mar go dorsi incurvatus, ventrcdis late excurvatus, posticus inter 

 alam dorsalem et extremitatem posteriorem valde simcatus ; pagina 



1 Bull. Sop. mnlacol. France, 1889, vol. vi. p. .38. 



