42 THE FAUNA OF THE DEEP SEA 



ance with the character of the coasts in their vicinity. 

 It is not necessary to give a detailed account of them, 

 but a few remarks on some of the more pronounced 

 forms may not be without interest. 



The blue mud contains eighty per cent, of a mix- 

 ture of quartz, mica, felspar, hornblende, and other 

 minerals, mixed with a considerable quantity of de- 

 composing animal and vegetable substance, the cal- 

 careous remains of foraminifera, niollusca, worms, 

 echinoderms, alcyonaria and corals, and the siliceous 

 skeletons of radiolaria and diatoms. 



The green mud is characterised by a large per- 

 centage of glauconite. 



The red muds characteristic of the Brazilian 

 coast contain a large amount of ochreous matter 

 brought into the sea by the great rivers. 



In the neighbourhood of active volcanoes there is 

 a characteristic volcanic mud, and in the coral seas 

 the deep-sea deposits contain a large percentage of 

 the calcareous remains of dead corals. 



One more character of the deep-sea region must 

 be referred to before we pass on, and that is the 

 absence of vegetable life. It has not been determined 

 yet with any degree of accuracy where we are to 

 place the limit of vegetable life, but it seems probable 



