THE TANGANYIKA PROBLEM. 221 



Nassoftsis, and Tanganyicia as well as for the two new 

 and very striking genera to which I gave the names 

 Bathanalia and Bythoceras. During the second Tangan- 

 yika expedition I obtained the material for the investiga- 

 tion of a further number of these forms, namely, Melania 

 admirabilis, Chytra, Paramelania damoni, Paramelania 

 crassigranulata, Stanlcya, and a new species of the genus 

 BytJioceras. No new generic forms were added during 

 the second Tanganyika expedition, and I think it very 



Fig. 2. — Living Typhobia horei. 



doubtful whether any more will be obtained in the lake. 

 At the present time, then, there remains only Syrnolopsis, 

 the anatomical affinities of which cannot be decided. 

 Accounts of the anatomical characters of several of the 

 halolimnic gastropods have already appeared by me in the 

 Proceedings of the Royal Society, the Quarterly Journal 

 of Microscopical Science, and in the Proceedings of the 

 Zoological Society, but, owing to our departure in 1899 

 on the second Tanganyika expedition, these descriptions 



