DISPERSION OF FRESH-WATER FISHES. 1 29 



faunae of Lake Tahoe and Utah Lake must be 

 chiefly due to influences which have acted since 

 the glacial epoch, when the whole Utah Basin was 

 part of the drainage of the Columbia. 



Connected perhaps with changes due to glacial 

 influences is the presence in the deep waters of the 

 Great Lakes of certain marine types, 1 as shown 

 by the explorations of Professor Sidney I. Smith 

 and others. One of these is a genus of fishes, 2 of 

 which the nearest allies now inhabit the Arctic 

 Seas. In his review of the fish-fauna of Finland, 3 

 Professor A. J. Malmgren finds a number of Arctic 

 species in the waters of Finland which are not 

 found either in the North Sea or in the southern 

 portions of the Baltic. These fishes are said to 

 " agree with their ' forefathers ' in the Glacial 

 Ocean in every point, but remain comparatively 

 smaller, leaner, almost starved." Professor Loven 4 

 also has shown that numerous small animals of ma- 

 rine origin are found in the deep lakes of Sweden 

 and Finland as well as in the Gulf of Bothnia. 

 These anomalies of distribution are explained by 

 Loven and Malmgren on the supposition of the 

 former continuity of the Baltic through the Gulf 

 of Bothnia with the Glacial Ocean. During the 

 second half of the glacial period, according to 

 Loven, " the greater part of Finland and of the 



1 Species of Mysis and other genera of Crustaceans, similar 

 to species described by Sars and othfcrs, in lakes of Sweden and 

 Finland. 



2 Triglopsis thompsoni Girard, a near ally of the marine species 

 Acanthocottus qitadricornis L. 



3 Kritisk Ofversigt af Finlands Fisk-Fauna: Helsingfors, 1863. 



4 See Giinther, Zoological Record for 1864, p. 137. 



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