458 Evolution and Distribution of Fishes 



and that complete continuity of Africa and S. America 

 through Tasmania with S. E. Australia was not of long 

 duration; while with N. Zealand, Norfolk Island and New 

 Caledonia connection was earlier and even shorter. 



Illustrations from the animal kingdom will at present 

 be restricted to the group of fishes. Pseudaphritis is a 

 monotypic genus of S. E. Australia, that includes the one 

 species P. iirvilUi. It is found in streams of that region, 

 and according to Regan (256:29) it "most nearly repre- 

 sents the prototype of the whole group." Now the family 

 is that of the Nototheniidae, that is referred to above (p. 

 455). It is closely related again to the Leptoscopidae, that 

 includes the freshwater alpine genus Clumarrh'ichthys of 

 New Zealand that is "remarkably adapted for living in 

 alpine torrents." Now Pseudaphritis is regarded by Regan 

 as the most primitive genus of the sub-family Bovichthyidae 

 that includes also Cottoperca and Bovichthys. Species of 

 both of these extend from the shores of S. E. Australia 

 and N. Zealand to St. Paul, Tristan, the Falklands, and 

 Magellan on to Chile, though none pass into antarctic seas. 

 But the derivative and more evolved sub-families Noto- 

 theniidae, Bathydraconidae, and Chaenichthyidae have 

 gradually split up into genera that not only are represented 

 along the shores or in the deep waters surrounding all of 

 the above localities, but also are around Marion, Kerguelen, 

 and Heard Islands, while what can only be regarded as 

 derivative species from these, and belonging mainly to the 

 genera Notothenia, Trematomus, Artedidraco etc., have 

 gradually migrated southward as truly antarctic species. 

 The striking enlargement of the eyes, as figured by all of 

 the authors referred to above, in many of these fishes that 

 have become deep-sea inhabitants should be recalled, as 

 examples of specialized evolution through environal action 

 and pro-environal response. 



But it might be objected to the above reasoning, that 

 the entire series originated in Chile or Fuegia as marine 

 fishes, which by degrees spread eastward to Australia, and 

 there gave off, as imigrants into freshwaters, the ancestors 

 of the morphologically more primitive Pseudaphritis. To 

 this practically impossible happening one can only reply 



