THE TANGANYIKA PROBLEM. 



343 



the greater number of the species of the Mormyridse are 

 endemic in the Congo. 



On the whole, then, these facts appear to indicate that 

 Tanganyika was originally stocked with halolimnic animals 

 from a western sea, of which the great lake itself, and the 

 vast back-waters of the Congo, may be said to be the last 

 remains. From these regions, those fishes which were able 

 to withstand the vicissitudes imposed by the physical 

 changes which have brought about the modern appearance 

 of the Continent, have wandered in all directions, varying 



Example of a typical Pyrgulifera from the 

 upper chalk of Ajka. From a specimen in the British Museum. 



as they went. But the bulk of the species of these fish are 

 still found confined within this region even to the present 

 day. 



It simply remains for us now, therefore, to ascertain 

 whether there is anything in the nature of the halolimnic 

 animals still surviving in Tanganyika, which will enable us 

 to determine to what age and type of sea-fauna they 

 belong. 



It has been seen that one of the characteristic anatomical 

 features of the animals belonging to the halolimnic group is, 

 that they all possess characters which could be ascribed to 

 the ancestors of numerous existing marine forms, or, in other 



