ioo STUDIES IN INSECT LIFE, ETC. 



While the main area of the Atlantic is covered 

 by the Globigerina ooze, there are a few small 

 tracts off the western coast of northern Africa 

 and around the Azores where this deposit is 

 replaced by the shells of certain floating or pelagic 

 molluscs known as Pteropods. Again there are 

 comparatively large tracts, one forming a wide 

 and irregular ring round the Bermudas, another 

 an irregular patch to the west of the Canaries, 

 in which Red Clay takes the place of Globigerina 

 ooze. Red Clay is much more abundant in the 

 Pacific ocean and is probably the most widely 

 distributed of all deep-sea deposits. Usually of a 

 reddish colour, at times it passes into a dark 

 chocolate hue due to the presence of a number of 

 small grains of pyroxide of manganese. As a 

 rule Red Clay contains little or no calcareous shell 

 matter, but flinty or siliceous organisms, sponge- 

 spicules or the skeletons of Radiolaria or of Dia- 

 tomes are often to be found in it. The most 

 constant of its inorganic elements are pumice in 

 all stages of disintegration, and oxides of iron and 

 manganese nodules. These, either as minute 

 granules or as secretions round other remains, not 

 infrequently attain the size of marbles. 



In certain circumstances, and if exposed for 



