THE NATURAL HISTORY OF THE SEA. 385 



as a hand-book, together with a brief account of the re- 

 sults of the Challenger Expedition) a detailed summary of 

 results obtained at all the observing stations, making a 

 scientific log of the voyage as well as an index to the 

 special memoirs. The summary occupies the main part 

 of the two volumes, and is illustrated with a series of 

 valuable maps and sections. Following the summary is 

 an analysis of the bathymetrical and geographical distribu- 

 tion, itself a gigantic labour, an index of the genera and 

 species, and a general index. These are labours the out- 

 come of which will appear only when years of reference to 

 them will have proved their value. The present interest 

 lies in the much too brief general observations Dr. Murray 

 permits himself to make. One result that was perhaps 

 little expected is that only a relatively small percentage of 

 deep-sea animals have a wide distribution over the floor of 

 the ocean. Alexander Agassiz, as the result of work with 

 closing tow-nets in the Albati^oss so recently as 1891, 

 concludes that " in the open sea, even when close to the 

 land, the surface pelagic fauna does not descend beyond a 

 depth of 200 fathoms, and that there is no intermediate 

 pelagic fauna living between that depth and the bottom, 

 and that even the free swimming bottom species do not rise 

 to any great distance, as we found no trace of anything 

 within sixty fathoms from the bottom, where it had been 

 fairly populated". He thinks, however, that "in a com- 

 paratively closed sea, at a small distance from the land, 

 there may be a mixture of the surface species with the deep 

 sea bottom species". Ur. John Murray, however, states 

 that : " The tow-net experiments carried out on board the 

 Challenger during several years in all parts of the world 

 led me to the conviction that these intermediate regions 

 were inhabited, although with a much less abundant fauna 

 than the waters near the bottom or those near the surface 

 of the ocean". It is plain that there is here a field for 

 future experiment and observation, especially when a trust- 

 worthy closing tow-net shall have been invented, — a simple 

 one that may be used without waste of time and temper. 

 Dr. Murray proceeds to contend that the organisms obtained 



