Literature Cited 



Berg, Leo S. (1933) : Die bipolare Verbreitung der Organismen und die Eiszeit. 

 Zoogeographica, 1, 444-484. 



Ekman, Sven (1935) : Tiergeogvaphie des Meeyes. Akademische Verlagsgesell- 

 schaft, Leipzig. 542 pp., illustr. 



Garman, Samuel (1899) : Reports on an Exploration Off the West Coast of 

 Mexico, Central and South America, and Off the Galapagos Islands, in Charge 

 of Alexander Agassiz, by the U.S. Fish Commission Steamer "Albatross," 

 During 1891, Lieut. Commander Z. L. Tanner, U.S.N., commanding — XXVI : 

 The Fishes. Mem. Mus. Comp. Zool. Havai-d Coll., 24, 1-431, 99 pis. 



Norman, J. R. (1937) : Coast Fishes — Part II : The Patagonian Region (In- 

 cluding the Straits of Magellan and the Falkland Islands). Discovery Repts., 

 16, 1-150, figs. 1-76, pis. 1-5. 



(1938) : Coast Fishes— Part III : The Antarctic Zone. Ibid., 18, 1-105, 



pi. 1. 



Summary of Discussion 



Professol- Yoiige cited as an example of the ease with which temperate 

 forms traverse tropical regions, the recent appearance of the New 

 Zealand barnacle Elminitis modestus in docks in Britain. Further, he 

 inquired whether a full analysis had yet been pubhshed of the situation 

 in the upper part of the Gulf of California where an isolated population 

 is locked in, corresponding to that of the same latitude outside, but 

 differing from that at the opening of the gulf. An analysis was still 

 being made and would shortly appear in published form, it was stated. 



Dr. Johnson mentioned the extraordinary case of barnacles being 

 transported overland to the Salt Lake of Utah. Mr. Powell stated that 

 Dr. Hubbs had very conclusively answered the question to be raised 

 by him in his paper following, as to whether some bipolar animals may 

 or may not go deep in the tropics and as to routes of convergence followed 

 between north and south. 



CERTAIN BIPOLAR ELEMENTS IN MARINE MOLLUSCS 



By A. W. B. Powell, Auckland Institute and Museum 



"" - . [AhstracV^ 



These notes are extracted from a report in preparation on the 

 Antarctic and subantarctic MoUusca collected by the " Discovery " 

 Committee expeditions during the years 1926 to 1937. * 



The material studied is largely from the American Quadrant. It 

 seems evident that — 



[a] The greater part of the southern high latitude molluscs have 

 been derived per the American Quadrant ; and 



{h) That the route was, and still remains, the continuity of the 

 west coast of the Americas plus the " Scotia Arc " bridge to 

 Graham Land and for certain deep-water genera the 

 Atlantic - Indian Ocean Cross Ridge which extends eastwards 

 between the Argentine Basin and the Atlantic Antarctic 

 Basin, almost to the Kerguelen-Gaussberg (radial) ridge. 



Three gasteropod genera — Aforia, Fusitriton, and Acanthina — are 

 instanced. 



* A. W. B. Powell, 1951, Discovery Reports, Vol. 26, pp. 47-196 



329 



