The Tanganyika Problem Reviewed 479 



The Cyprinidae of Tanganyika seem to be the most 

 far-travelled of its teleostean families. For though con- 

 sisting only of eight species, referable to the three genera 

 Barhus, Banlius, and Capoeta, these all show greatest 

 affinity with, and derivation from, others that entered 

 Africa from the east. The probable line of travel has been 

 already traced (p. 417). They may have entered Africa 

 during the early Oligocene, and spread westward to Tan- 

 ganyika. Later, as elevation of Tanganyika, of Lake 

 Victoria, and of Lake Albert, brought these to a level with 

 the head waters of the Congo, an added westward migra- 

 tion became possible. 



Some additional features of interest shown by Tangan- 

 yika and the other African lakes, as compared with S. 

 America, may now be treated of. The Aspredinidae with 

 22 species, the closely related Loricaridae with fully 200 

 species, the Gymnotidae with 31 species, and the Atherin- 

 idae with 33 species, are all absent from Africa. These 

 are all highly evolved families, and at least the first three 

 seem to have appeared originally over the Archandean con- 

 tinent. So when union of it and Archenchelis took place, 

 and migration of the above families went on into Eastern 

 Brazil, land connection with West Africa was probably 

 sundered, and so eastward migration into Africa was im- 

 possible. 



But the two important and thoroughly freshwater fami- 

 lies, Mormyridae and Mastacembelidae, that are unrepre- 

 sented in America, are decidedly puzzling in their African 

 distribution. The former is a purely African family, and 

 includes upwards of 60 species, some of which are native 

 from Senegal and Gaboon across the continent to the Nile. 

 For some time it was supposed to be absent from Tangan- 

 yika, but Mormyrus longirostris, and Marcusenius tangani- 

 cus now found there, furnish proof that the family is of 

 fairly ancient ancestry and rather wide distribution. The 

 former also is one of the simplest genera, the latter one of 

 the most evolved genera (227:53). Boulenger further 

 has suggested a close affinity between the Mormyridae and 

 Albulidae. But in spite of some marked differences, the 

 writer would suggest a closer affinity even with the Osteo- 



