THE TANGANYIKA PROBLEM. 229 
by Miss Digby.* Originally the empty shell had been 
described and figured by Smith in the Proceedings of the 
Zoological Society for 1881, and was placed by him in the 
genus Limnotrochus, together with Limnotrochus thomsoni 
Fig. 11. — The shell of Chytra kirkii. From the side and from below ; 
slightly enlarged. 
In 1897, however, I had occasion to show that the latter 
form not only differs considerably from kirkii, but is also 
comparable to the old Jurassic fossil known as Littorina 
sulcata, whereas kirkii closely resembles some of the 
Fig. 12.— Living animals of Chytra kirkii. 
Jurassic Xenophoridse. On this account I separated kirkii 
from Limnotrochus altogether and placed it in the new 
genus Chytra. The investigation of the anatomy of Chytra 
Miss L. Digby, “Journal of the Linnean Society,” 1902. 
