THE CARP POND. 141 



cyprinoids have spread over the whole of the 

 old Continent and of North America. But 

 the sea forms the great barrier in the way of 

 migration for fresh-water creatures ; so that 

 they have not yet been able to get beyond 

 the limits of this northern land-surface, long 

 united in a single continent by the elevation 

 of the Icelandic bank. Australia we know 

 has never been joined to Asia or the rest of 

 the world since the cretaceous period at least, 

 and therefore there are no cyprinoids in 

 Australia. South America has only recently 

 been linked to the northern continent by the 

 elevation of the narrow mountain belt at 

 Panama which causes so much trouble to 

 M. de Lesseps, and it still preserves for the 

 most part its own very antiquated and 

 isolated fauna of llamas, alpacas, armadillos, 

 sloths, and ant-eaters ; so that into South 

 America too the cyprinoids have not yet had 

 time to penetrate. Of course they are equally 

 absent from the islands of the Pacific, cut off 

 as those oceanic archipelagos are from all the 



