Over a South Atlantic Continent 433 



along the S. Atlantis and Afro-Indian bridge to India. Or 

 in the latter case the evolving species spread from Africa 

 both westward into Brazil and eastward into India. By 

 subsequent organic denudation, both groups have disappear- 

 ed from Africa, but in India they not only persisted, they 

 extended northward to China-Japan, and southward they 

 reached Australia and Tasmania during that relatively 

 recent and short period when Malaya, Australia and Tas- 

 mania were more or less continuous. During this short 

 period also the more evolved Australian marsupials — that 

 had migrated from America along another passageway 

 described below — passed northward from that Island 

 (p. 141) into Malaya, and this at a much later time than 

 when they first entered Australia by its south and S. E. 

 coasts. 



But such an explanation in no way applies to the species 

 of Galaxidae and Aplochitonidae, whose distribution is al- 

 most identical, except that none of the latter group occurs 

 with the former in S. Africa. Before dealing in detail 

 with them, it may be well to observe that fishes from the 

 Southern Hemisphere have at times been reported as fresh- 

 water that do not deserve such a designation. For they are 

 all southern outliers of more northern marine genera, that 

 occasionally pass into the mouths of rivers. A case in point 

 is the list of "Freshwater species" that succeeds the much 

 longer list of "Marine Species" collected by Mr. Gulliver 

 at Rodriguez (26^:471). 



The question Involved In distribution of the Galaxidae 

 and Aplochitonidae is a very large one from every biologic 

 and geologic standpoint. So the writer proposes to deal 

 somewhat fully with it In the remainder of this chapter. 

 Attempts have been repeatedly made to get over the difii- 

 cultles of the case, by supposing that the above two families 

 were derived from a marine ancestry, as has In part been 

 Indicated above. But the effort invariably leads one into 

 strained and even quite unscientific views. The question 

 then is : How are we to explain the existence In freshwaters 

 of lower S. America, of the Falkland Islands, of extreme 

 S. W. Africa, of New Zealand, Tasmania, and of widely 



