492 DR MURRAY ON THE DEEP AND SHALLOW-WATER MARINE FAUNA 



been argued that in ancient times marine animals might have secreted massive lime 

 structures in cold water, but from the considerations stated above this may be regarded 

 as impossible. 



The absence of all the pelagic larva? of Benthos animals from the tow-net gatherings 

 in the cold Antarctic and Arctic waters is another striking fact, as these are universally 

 present within the tropics. The Benthos animals of the cold waters of the polar regions 

 appear to have in nearly all cases a direct development, and the same appears to be the 

 case with deep-sea animals. When coral reefs flourished within the Arctic circle, we 

 must suppose that there was associated with them a large number of a,nimals with pelagic 

 larvae, as we find in the coral-reef regions of the present day. 



Instances of identical species occurring at Kerguelen and on the coasts of Europe are 

 frequently referred to in the notes to the foregoing lists, and in some cases it has been 

 supposed that these animals may have been carried on ships' bottoms from the one 

 hemisphere to the other, but no such explanation can now be entertained, so numerous 

 are the cases of identical species occurring in the far north and in the far south, and not 

 present in the intermediate torrid zone. From very early times the general similarity 

 between the whales, seals, and birds in the Arctic and Antarctic areas has been the subject 

 of remark, and this was attributed to similarity in the physical conditions in the two 

 polar areas. 



The first dredgings and trawlings conducted by the Challenger in comparatively 

 shallow water in the extra-tropical regions of the Southern Hemisphere were those about 

 the Tristan da Cunha group of islands. Concerning these Wyville Thomson wrote at the 

 time : " These shallow- water dredgings around Tristan da Cunha gave a great amount of 

 material, the fauna being very much of the same character as that of somewhat shallower 

 water in the north. The species seem in many cases to be identical, but this will require 

 critical examination to determine." This impression was deepened by further trawlings 

 towards the Antarctic, and has been confirmed by the specialists who have reported on 

 the several groups of marine organisms. In the Summary volumes of the Challenger 

 Report I have given lists of the identical species found in the temperate and cold 

 regions of the two hemispheres, but not recorded from the intervening tropical zone. 

 In the present paper further lists are given of identical and closely-allied species which 

 occur in the Kerguelen Region and other areas of the southern hemisphere, and in the 

 northern hemisphere north of the tropic of Cancer, but not within the tropics. Indeed, 

 the marine fauna of high southern latitudes is more closely related to the marine fauna of 

 high northern latitudes than to any fauna in the intervening regions. This is all the 

 more remarkable when we remember that there is hardly a single species of marine 

 Benthos Metazoa common to the east and west coasts of Africa within the tropics, if we 

 except some brackish water and deep-sea species. 



In an interesting paper on Arctic and Antarctic marine floras, George Murray 

 and E. S. Barton write: "Nothing is more striking in the distribution of seaweeds 

 than the change from our northern Fucacece to the Sargassa and other allied genera 



