THE TANGANYIKA PROBLEM. 
221 
N as sop szs, and Tanganyicia as well as for the two new 
and very striking genera to which I gave the names 
B athonoha 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 , P aramelania damoni , Paramelania 
cr assign anulata, Stanleya, and a new species of the genus 
Bythoceras. No new generic forms were added during 
the second Tanganyika expedition, and I think it very 
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 
