Over a South Atlantic Continent 431 



CHAPTER XV. 



Fishes in Relation to A South Atlantic Continent. 



The writer has reserved for separate discussion, a small 

 series of teleostean families that are puzzling in their 

 geographic distribution, that often undergo marked struc- 

 tural modification, that indicate frequent points of contact- 

 relation with the families studied in last chapter, and which 

 also suggest past geologic conditions and land-connections 

 that some may regard as too extreme for acceptance as yet, 

 or until more abundant confirmatory evidence is secured. 



We refer to the Galaxidae, the Aplochitonidae, the 

 Symbranchidae, the Amphipnoidae, and the Anguillidae. 

 The first four of these are freshwater, the last is fresh- 

 water, brakish, or mainly marine. The geographic distribu- 

 tion of the first four is arresting, of the fifth confusing, un- 

 less some exact line of action can be shown to be in opera- 

 tion. So if the main contentions of this volume are correct, 

 some light should be shed on their origin. 



Regarding the Galaxidae Boulenger says (252:84) 

 that "eight are known from N. Zealand and the neighbor- 

 ing islands, seven from N. S. Wales, three or four from 

 South Australia, one from West Australia, two from Tas- 

 mania, seven from S. America from Chile southwards, and 

 one from the Cape of Good Hope." At the same time he 

 records the finding of "a marine Galaxias" that "was taken 

 out of the mouth of a specimen of Merganser austraUs 

 during the collecting excursion to the southern islands of 

 New Zealand." In this connection also he sounds a note 

 of warning against regarding the Galaxidae as freshwater 

 in origin, specially seeing that one native to the Falkland 

 Islands and to N. Zealand "periodically descends to the sea, 

 where it spawns, from January to March, and returns from 

 March to May" to the freshwaters. The question then 

 here is: Should we regard the 28 freshwater species (now 

 increased to 30), found in seven widely apart localities, 

 as freshwater derivatives from a marine genus, of which at 

 most two species are catadromous, or are seashore dwellers. 



