﻿240 MR. E. BULLED NEWTOK ON FOSSIL [May I9IO, 



above the water-level, as well as 3 miles west of that village at 

 the altitude of 350 feet above the same level, where they occur as 

 marl-casts, and again at Chisali, 15 miles west of the lake, at an 

 elevation of 400 feet, where their casts form a limestone of some 

 durability. Examples of Lanistes were collected at Chiwondo from 

 a height of 20 feet, in association with well-preserved Viviparus. 



The terrestrial shells are localized from Chiwondo and Masiunjuti, 

 the latter place being situated some 12 miles west of the lake- 

 margin, where the specimens were found on the top of the sands 

 and marls. 



The Chisali specimens appear, however, to be of greatest interest, 

 since they indicate a considerable north-westerly extension of 

 Lake ISTyasa in Quaternary times. They occur as casts in a cream- 

 coloured limestone, where all evidence of shell-structure has been 

 dissolved away, although, from wax impressions of the more perfect 

 natural moulds, it has been possible to determine, with a fair amount 

 of certainty, their relationship to Viviparus unicolor, a present-day 

 inhabitant -of Lake Nyasa and other freshwater regions of Africa. 



Freshwater Forms. 



Genus Viviparus, Montfort. 



' Conchyliologie Systematique ' 1810, vol. ii, p. 246. 



Type=Helix vivipara, Linn. 



Sj'nonym: Vivipara, Lamarck, 1809 [=list-name onlyj. 



Yivipartjs unicolor (Olivier). (PI. XVIII, figs. 1-5.) 



Cyclostoma unicolor, Olivier, ' Voy. Emp. Oth. Egypte, Perse' 1804 (=An xii) r 



vol. iii, p. 68 & atlas, pi. xxxi, fig. 9. 

 Vivipara capillata, robertsoni, Jeffrey si, von FrauenfeLd, Verhandl. Zool.-Bot. 



Gesellsch. Wien, 1865, vol. xv, pp. 632-33 & pi. xxii. 

 Vivipara unicolor, Jickeli, Nova Acta K. Leop.-Carol. Deutsch. Akad. Naturf. 



vol. xxxvii (1874) p. 235. 

 Paludina unicolor, Blanckenhorn, Zeitschr. Deutsch. Geol. Gesellsch. vol. liii 



(1901) p. 432. 



The few isolated examples of this species in the collection are 

 somewhat worn, otherwise they exhibit the basal angulation and 

 some obscure spiral sculpture. They compare favourably with 

 Olivier's original figures and with Jickeli's later descriptions in 

 possessing about six whorls, the earlier being more or less con- 

 tabulate, while the basal bears an obscure angulation. 



So far as dimensions are concerned, they also correspond with 

 those given by Jickeli, the largest specimen having a height of 

 nearly 25, a maximum diameter of 18, and an aperture measuring 

 12 by 10 millimetres. 



In making this determination, the broadest view of Olivier's 

 unicolor has been adopted, since the species has hitherto been 

 regarded as belonging chiefly to Nile waters and not forming part 

 of the Nyasa fauna. A careful comparison of forms in the Zoolo- 

 gical Department of the British Museum has, however, induced me 



