ARCTIC ZOOGEOGRAPHY l6l 



As a matter of fact there has been more controversy over its extent, and 

 over the question whether there has been more than one such con- 

 nection within recent geologic times, than over its having existed at 

 all. Gradually a route over the Aleutian chain, as at present con- 

 stituted, has been eliminated, but, on the other hand, a possible 

 connection to the north of Bering Strait is still awaiting a thorough 

 investigation. As for the possibility of several openings and closings 

 of the gap between the two continents and the mingling of the waters 

 of the Arctic Basin with those of the Pacific, the deciding arguments 

 must come from the minute study of the distribution, past and present, 

 of the marine invertebrates. 



The Alaska Blackfish as Evidence of a Bering 

 Land Bridge 



That there has been a rather early continuity of land is almost 

 beyond dispute if we consider the occurrence of the so-called "Alaska 

 blackfish " (Dallia pectoralis) , named after one of the earliest and most 

 celebrated students of the problem, the late Dr. W. H. Dall. This is a 

 truly Arctic fresh-water fish and for this reason deserves a more extended 

 mention in this connection. It was first described under the above 

 name in 1879 by T. H. Bean^ from specimens collected at St. Michael, 

 Alaska. Two years later Smitt,^'^ in Stockholm, described the same 

 species from specimens collected by Nordenskiold's Vega expedition 

 near the wintering station at Pitlekai, on the north coast of the 

 Chukchi Peninsula, under the name Umbra delicatissima. In "The 

 Voyage of the Vega "^^ Baron Nordenskiold gives the following account 

 of this fish : 



"In the fresh-water lagoon at Yinretlen ... we caught by 

 hundreds a sort of fish altogether new to us, of a type which we should 

 rather have expected to find in the marshes of the Equatorial regions 

 than up here in the north. The fish were transported in a dog sledge 

 to the vessel, where part of them was placed in spirits for the zool- 

 ogists and the rest fried, not without a protest from our old cook, who 

 thought that the black slimy fish looked remarkably nasty and ugly. 

 But the Chukches were right: it was a veritable delicacy, in taste 

 somewhat resembling eel, but finer and more fleshy. These fish were 

 besides as tough to kill as eels, for after lying an hour and a half in the 

 air they swam, if replaced in the water, about as fast as before. How 

 this species of fish passes the winter is still more enigmatical than the 



8 T. H. Bean: Description of Some Genera and Species of Alaskan Fishies, Proc. U. S. Natl. Museum, 

 Vol. 2, 1879, pp. 353-359; reference on pp. 358-359. 



1° F. A. Smitt, Ofversigt af Svenska Vetenskapsakad. Forhandl., Vol. 38, 1881, No. 5, p. i and PI. 5, 

 Fig. I. 



" Amer. edit., New York, 1882, pp. 442-444; British edit., 2 vols., London, 1881, reference 

 in Vol. 2, p. 58. 



