1906.] OF THE THIRD TANGANYIKA EXPEDITION. 181 



to Mr. J. E. S. Moore *, were found by him, respectively, only at 

 the south end and more northern localities. 



Living examples were obtained of Limnotrochihs, Tijjhohia, 

 Bythoceras, Paramelania, Lavigeria, Edgaria, Giraudia, and 

 Anceya ; and these it is proposed to place in the hands of an 

 experienced anatomist for investigation. The last three of these 

 thalassoid genera have not been anatomically examined, and 

 therefore it will be of interest to know their relationship and 

 systematic position, and it will also be interesting to see if the 

 conclusions arrived at, in respect of the rest, coincide with the 

 results of Mr. Moore's investigations of them. In concluding 

 these prefatory observations on the marine-like forms, I would 

 again t call attention to the fact that M. Bourguignat had em- 

 ployed the term " thalassoid " in connection with them long before 

 the invention of the compound " halolimnic " by Mr. Moore. 



Among the ordinary freshwater forms, the discovery of a 

 species of Ancylus, the first from the lake, is of interest. This 

 genus has been recorded from the Victoria Nyanza, but not from 

 the other large lakes of Central Africa. Being, however, such 

 small objects, and difficult of observation, they may have easily 

 been overlooked +. 



Of the few species obtained by Dr. Cunnington in the Victoria 

 Nyanza, two appear to be new, namely, a Corhicula and a 

 Sphcerium, both closely allied to one or other of the few forms 

 already known from this lake. 



I. Species from Lake Tanganyika. 

 a. Thalassoid Species. 



1. Chytra kirkii (Smith). 



Hah. Tembwi, a little below middle of west coast, 20 fath. 



2. Bathanalia howesi Moore. 



Eah. Niamkolo, south end of lake. 



The dimensions of this species, which have never been stated, 

 are: — Length 30 millim., diam. 22; aperture llg long, 10 broad. 



3. Limnotrochus thomsoni Smith. 



Hah. Ndanvie, east coast towards the north end of the lake, 

 10 fathoms, also at south end. 



4. TiPHOBiA horei Smith. 

 Hah. Kala, at south end of lake. 



* ' Tlie Tangaiij'ika Problem,' p. 149. 



t See Proc. Malac. Soc. vol. vi. p. 78. 



X M. Louis Germain has recently briefly described from Tanganyika new species 

 of Planorhis, Vivipara, and Cleopatra. Bull. Mus, Hist. Nat. Paris, 1905, no. 4, 

 pp. 254-261. 



13* 



