FRESH-WATER FISHES— MYERS 349 



have pushed up into Central America. The only other South 

 American fresh-water fishes of the primary class are the lungfishes 

 (one species)'* and the nandids (two genera and two species). ^^ 



Of the secondary class of fresh-water fishes, the most numerous 

 in South America are the cichlids ; the genera seem to be more diverse 

 than the African ones, though the number of species is smaller. The 

 cyprinodonts have already been mentioned. 



In order that the reader may appreciate the evident relationship 

 with Africa displayed by many South American fishes, it is necessary 

 to add a few words on the Ethiopian fish fauna. This is definitely 

 composed of two main elements, one a group of primitive and un- 

 doubtedly ancient fish families that are unknown outside Africa either 

 fossil or recent and that in all likelihood evolved there, and a pre- 

 ponderating fauna of migrants which reached and flooded the conti- 

 nent in later times. To the old group belong the bichirs, pantodonts, 

 phractolaemids, kneriids,^^ and mormyrids. Undoubtedly existing 

 there with them were the old ubiquitous osteoglossids, which may 

 have given rise to the pantodonts and of which a single species still 

 persists today. To the later invaders belong the teeming present-day 

 African characins (of two families, one held in common with South 

 America), ciclilids, labyrinth fishes, carps, and certain catfishes. The 

 carps undoubtedly arrived only in the middle or late Tertiary from 

 southern Asia; their many species have mostly not yet become gener- 

 ically distinct from their Asiatic relatives. The characins and most 

 of the catfishes were undoubtedly present in Africa before the arrival 

 of the carps. Some of the families of catfishes (electric catfishes, 

 mocholdds, and amphiliids) and one of characins (citharinids) prob- 

 ably evolved there, the latter certainly out of the Characidae. The 

 Characidae, cichlids, nandids, rivuline cyprinodonts, lungfishes, and 

 osteoglossids are held in common with South America, but it has 

 already been noted that the last-mentioned family is probably of no 

 great importance in this connection, and the same is possibly true of 

 the lungfishes. It is of especial importance to note that not one of 

 five primitive, autochthonous, African families, that were in all prob- 

 ability in Africa before the characins, cichlids, and carps, are held in 

 common with South America. 



>* Lepidoshen. The only other living species of Lepldosirenidae are the three Protopterus of Africa. 

 The Australian Neocerafodus is very dillerent. 



" Polycentrus and Monocirrhus are closely related to the Nigerian Polycentropsis and the Indian Nandua. 

 The Indian Badis is very distinctive and probably should form a separate family. It is close to neither 

 Nandus nor Pristotepis. 



" Following up Pellegrin's recent comparison of the peculiar Nilotic cromeriids with larval albullds, and 

 his hesitant suggestion of kneriid relationship, I shall be greatly surprised if CromeTia is found to be any- 

 thing but a larval Kneria. 



