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 1 88 1, and was placed by him in the 

 genus Limnotrochus, together with Limnotrochus tJwmsoni 



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. 



