OF THE KERGUELEN REGION OF THE GREAT SOUTHERN OCEAN. 487 



Concluding Remarks. 



The principal object in view in this paper has been to exhibit the present state of 

 knowledge concerning the deep-water and shallow-water marine faunas of the Kerguelen 

 Region of the Great Southern Ocean, and to compare these faunas with the deep-water 

 and shallow-water faunas in other regions of the ocean. In consequence of the researches 

 of the Challenger Expedition in 1873 and 1874, our knowledge of the faunal conditions of 

 the Kerguelen Region is more complete than that of any other area of the Great Southern 

 and Antarctic Oceans. In view of the possible more thorough exploration of the south 

 polar regions in the near future, it has seemed desirable to summarise our knowledge of 

 the marine organisms of the Kerguelen area, for the use of those who may be engaged in 

 Antarctic exploration, and to point out directions in which future investigations might 

 likely yield some interesting and important results. 



In the concluding volume of the Challenger Report, I have pointed out that an 

 analysis of the results obtained by the Challenger's trawlings and dredgings in different 

 parts of the world indicated certain general conclusions with reference to the distribution 

 of organisms over the floor of the ocean. It appears to be established by these investi- 

 gations that life is everywhere present on the sea-bed in all depths and at all distances 

 from the shore. The number of species in great depths far removed from land is very 

 small when compared with the number of species present in lesser depths near to the 

 shores of continents ; the number of species gradually increases towards the shallow 

 water of the continents, the greatest number being found in the whole area less than 50 

 fathoms surrounding the dry land. The proportion of species to genera is, on the whole, 

 larger in shallow than in deep water, the Challenger results giving a gradually decreasing 

 ratio from shallow water down to the greatest depths, as follows : — 



Over 2500 fathoms, ratio of species to genera = 1*17 to 1 



2000-2500 



J) )! 



1-36 



1500-2000 



55 3) 



1-45 



1000-1500 



" ) J 



1-50 



500-1000 



) J 5) 



T67 



100- 500 



55 5J 



2-37 



Under 100 



5) JJ 



2-93 



The Challenger researches did not indicate the existence of large numbers of individuals 

 belonging to any one species in deep water beyond 1000 fathoms. In lesser depths, 

 however, the number of individuals belonging to a single species was sometimes very 

 large ; and just below the 100 fathoms line, where on open coasts fine detrital matters 

 finally commence to settle on the bottom, enormous numbers of individuals belonging to 

 one species are present in, or on the surface of, the mud. A comparison of the species 

 captured in deep water in two widely separated areas under apparently similar condi- 

 tions did not show many species in common, and on the whole there was little evidence 



VOL. XXXVIII. PART II. (NO. 10). 3 T 



