136 
THE TANGANYIKA PROBLEM. 
Cichlids are on the whole primitive as far as that group is 
concerned. If, moreover, the above view of the origin of 
the Tanganyika fish-fauna be correct, the fact that the 
genera of Characinkke and Siluridaj living in Tanganyika 
are not endemic would be perfectly intelligible. The first 
of these groups is a very old one, and might easily have 
become a wandering fresh-water stock before Tanganyika 
became a land-locked depression ; while the second contains 
forms which are known to be capable of migration in a high 
degree. The same kind of reasoning thus obviously also 
applies to the non-endemic species of the latter group. 
Some such view of the case would at once explain other 
matters. If Tanganyika became stocked from an ancient 
western sea, this would account for the presence of Cichlidse 
in the Congo, and the presence of forms like bass only in 
the Congo, the Nile, and Tanganyika, as well as the 
existence of several species of the ancient ganoid Potypterus 
in these different waters. For it is a geographical fact, 
which should be clearly understood, that at certain times 
and at certain seasons it is possible to push one’s way in a 
boat from the upper tributaries of the Congo into those of 
the Nile, the watersheds in this region being extremely ill 
defined. 
Up to the present time there are known in Tanganyika 
the following series of forms : — 
FISHES. 
POL.YPTERID.iE. 
1. Polypterus congicus Blgr. 1898. 
Lepidosirenid.e. 
2. Protopterus sethiopicus Heck. 1851. 
Characinid^;. 
3. Hydrocyon lineatus Blkr. 1863. 
4. Alestes macrophthalmus Gthr. 1S67. 
5. ,, macrolepidotus C. & V. 1849. 
6. Citharinus gibbosus Blgr. 1899. 
Cyprinid.e. 
7. Capoeta tanganiccc Blgr. 1900. 
8. Barbus platyrhi>ius Blgr. 1900. 
9. ,, altianalis Blgr. 1900. 
10. ,, serriRr Blgr. 1900. 
11. ,, tropidolepis Blgr. 1900. 
12. Barilius moorii Blgr. 1900. 
13. ,, tanganica Blgr. 1900. 
