Ixiv. PRESIDENT'S ADDRESS. 



the mud, clay, or ooze, and by picking up the small organisms which 

 fall from the surface. Usually species are most abundant in the 

 shallow waters near land, decreasing in numbers with increasing 

 depth ; but in the polar regions there are indications of a more 

 abundant fauna in depths of 50 or 1 50 fathoms than in shallower 

 water under 50 fathoms. Foraminifera (minute animals belonging 

 to the sub-kingdom Orotozoa), all of which live abundantly at the 

 surface and at intermediate depths, and at death fall to the bottom, 

 making up with coccoliths and rhabdoliths, a small proportion of the 

 spines and tests of radiolarians and fragments of the spicules of 

 sponges, the globigerina-ooze. The shells of globigerina make up 

 three-fourths of the ooze, which occupies a belt of depths down to 

 2,000 fathoms round the shores outside the belt of shore-deposits. 

 About 20 per cent, of the ooze consists of coccoliths and rhabdoliths, 

 which are in all probability algse of a peculiar form, or their 

 sporangia. Passing on to deeper soundings, this calcareous forma- 

 tion is gradually replaced by an extremely fine clay at depths 

 below 2,500 fathoms, consisting almost entirely of a silicate of red- 

 oxide of iron and alumina. The transition is very slow, and extends 

 over several hundred fathoms of increasing depths. Wy ville 

 Thompson, director of the civilian staff of the "Challenger" 

 Expedition, concludes that the " red clay " is not an additional 

 substance introduced from without, but that it is produced by the 

 removal, by some means or other, of the carbonate of lime, 

 which forms about 93 per cent, of the material of the globigerina 

 ooze. 



The most remarkable result of the " Challenger " Expedition is 

 the final establishment of the fact that the distribution of living 

 beings has no limit, but that animals of all the marine invertebrate 

 classes, and probably fishes also, exist over the whole of the floor 

 of the ocean. The distribution of life evidently depends upon the 

 nature of the sea-bottom. Thus over the vast areas where it 

 consists of red or grey clays animal life is scarce, and is represented 

 by shell-less orders. The fauna at great depths is remarkably 

 uniform. Species nearly allied to those found in shallow water of 



