148 DEPTHS OF THE OCEAN 



sands. The benthonic deep-sea animals live by eating the mud 

 or ooze covering the ocean-floor, and appear to find all the 



Fig. 



Haliomma ivyvillei, Haeckel. 



From the surface (magnified). 



Animal 

 remains in 

 marine 

 deposits. 



Siliceous 

 remains. 



nourishment they require therein. The excreta of these animals 

 are associated with a certain amount 

 of slimy albuminoid matter, and in cer- 

 tain localities these excreta become so 

 numerous that the term " coprolitic 

 mud " has been proposed for the 

 deposits containing them. 



The animal remains found in deep- 

 sea deposits are either siliceous or 

 calcareous, those of a chitinous char- 

 acter being extremely rare, if not 

 entirely absent. The siliceous remains 

 of radiolaria (see Figs, no to 117) 

 and the spicules of siliceous sponges 

 are widely distributed over the ocean- 

 floor, the radiolarian skeletons being so abundant in certain 

 regions as to make up a very large part of the deposit, which 



Fig. 115. 

 Lithoptera darwinii, Haeckel. 

 From the surface (magnified). 



