4 - EINAR LÖNNBERG, (Schwed. Südpolar-Exp. 



corresponding manner masses of cold water and ice towards the south. In a similar 

 way an interchange of cold and warm water must take place in the south polar 

 region, and this gives an undulating boundary line to the true Antarctic Region, a 

 boundary line that cannot coincide with the Antarctic Polar Circle nor with any 

 other mathematical circle. Although the antarctic seas are not by far so well ex- 

 plored, neither hydrographicalh* nor in other respects, as the arctic. This has been 

 proved b)- the simple fact that it has been so much easier to progress towards the 

 south in some parts of the globe than in others. The boundary line of the Ant- 

 arctic life-zone cannot with the present state of our knowledge be laid out all around 

 the globe, but this does not matter so much for the present memoir which only 

 deals with fishes from the Atlantico-American quadrant. But within that same a 

 trial must be made to define to a certain degree the northern limit of the Antarctic 

 life-zone. When making this we have to consider the terrestrial as well as the 

 marine conditions. The latter are not so well known as yet as they will be when 

 the hydrographical material of this Expedition has been worked out and lies ready 

 before the scientific public. But some, and, as I think, for this purpose sufficient 

 facts, might already be gathered. A sea where the temperature in the summer from 

 the surface to the bottom in a depth of 1450 m. shows a temperature below zero 

 of the centigrade deserves to be termed "Antarctic". Such was the case in Brans- 

 field Strait at the end of Nov. 1903. The temperature at the surface was — 1,50 C. 

 and at the bottom — 1,65' C. * It is true that in an intermediate depth the tem- 

 perature rose somewhat, even slightly above zero, viz. -I- 0,02' C. in a depth of 

 300 m. from the surface, but this does not materially alter the pronounced fact that 

 Bransfield Strait is truly and purely antarctic and Dr. J. G. AnderssON calls it in 

 his narrative "the coldest marine area on the globe" (1. c. p. 167). The southern 

 coasts of the South Shetland Islands are thus bordered by this cold sea and the 

 sounds between them as well as their northern coasts are, for all we know, in the 

 summer surrounded by drifting pack ice, at least some years, and must therefore be 

 termed antarctic. The same holds good for the Joinville Island. The cold basin 

 of Bransfield Strait extends rather far east, but even beyond its eastern limit at 

 61 52' S. lat. 52 57' W. long, the bottom temperature in a depth of 1,631 m. was 

 found to be — 0,4' C, a temperature low enough to be called antarctic. That the 

 Erebus and Terror Gulf is truly antarctic as to its physical conditions may not be 

 disputed when it has been stated that it even in summer, at least some years, is 

 to a great extent covered by an unbroken sheet of sea ice. All this may be sum- 

 med up to the statement that the seas surrounding the South Shetland Islands, Join- 

 ville Island, Louis Philippe Land and the land and the islands to the south of these 

 are truly antarctic even if situated north of the Antarctic Polar circle. 



• J. G. ANDERSSON: >.\ntarctic>, tva àr bland sydpolens isar. Stockholm 1904. II p 166. 



