234 
THE TANGANYIKA PROBLEM. 
which corresponds in position and appearance to that 
encountered in the same place in Xenophora. 
The animal does not appear to be viviparous. 
LIMNOTROCHUS, SMITH. — LIMNOTROCHUS THOMSON I 
(fig. 17). 
As I have previously stated, the shell of this animal 
(Fig. 17) was originally described by Smith. During the 
first Tanganyika expedition, only one badly preserved 
Fig. 18. — The lingual dentition of Limnotrochus thomsoni (X 1 50)- 
specimen was obtained ; but during the second, five 
specimens in good condition were dredged, not, however, 
without much trouble and in the southern portion of the 
lake. As in the case of Chytrci, the anatomical material 
obtained was examined by Miss Digby, from whose 
results I have condensed the following description. 
The tentacles are shorter than in Chytra , and the snout 
and body more pigmented. The snout is short, and the 
buccal mass much farther back than in Chytra. The oper- 
culum is curiously oblong in shape, litterinoid and concave. 
