530 Evolution and Distribution of Fishes 



Falklands, they then migrated eastward along rivers and 

 lakes of the southern continent, somewhat ahead also of 

 the great marsupial migration of late Eocene and Oligocene 

 time. But all reached, first Tasmania and S. E. Australia, 

 later S. Africa and Malaya temporarily, and over this 

 entire region species of these two families of freshwater 

 fishes now survive along with the land marsupials that are 

 only absent from S. Africa. 



The distribution and mode of life of the species that 

 make up the genera of Galaxidae and Aplochltonldae are 

 then deal with, and all are viewed as constituting a fairly 

 compact biologic and geographic series that once overspread 

 Chile-Patagonla-Antarctica, and Tasmano-Australla. Evi- 

 dence however is adduced to show that at least In the case 

 of plants and to a slight degree of animals, a contempo- 

 raneous east to west migration was proceding. Thus a 

 westward migration of certain freshwater fishes can be 

 traced. But so far as we know these gradually took to the 

 sea during the migration process. Thus from Pseudaphri- 

 tis and Chimarrichthys to Cottoperca and Bovichthys one 

 can pass gradually to the south sea families Notothenildae, 

 Bathydraconidae, and Chaenichthyldae that are now wholly 

 marine. The remarkable and highly specialized forms of 

 Notothenia and allied genera, that now live In the abysses 

 of antarctic seas, represent the end members of a highly 

 evolved series. The writer then summarizes his conclusions 

 as to an antarctic continent and its associated fish fauna. 



Chapter i6. A Review of the Tanganyika Problem. 



The rich and peculiar fish-fauna of Tanganyika has 

 attracted the attention of many Investigators. Chief 

 amongst these are Moore and Boulenger. The former In 

 his suggestive volume entitled "The Tanganyika Problem" 

 brought forward many facts and new observations that 

 the writer now examines. The lists of perldlnlal, sponge, 

 medusold, polyzoan, crustacean, molluscan, and not least 

 of fish types, caused Moore and others to view the whole as 

 of marine origin. 



The writer accordingly takes up all of the organisms 

 in detail, except the molluscs, and shows that they are 



