256 EXPLANATION OF THE PLATES 



Densities between 1-024 and 1'026 are indicated by shades 

 of purple, while densities exceeding r026 are shown by 

 shades of red, and occur almost entirely beyond the 

 latitudes of 40° N. and S. It is in the areas of high 

 density (especially where the density exceeds 1-027 in 

 the North Atlantic and Southern Oceans) that the water 

 sinks beneath the surface to the greater depths, carrying 

 with it the atmospheric gases. 



Plate VII. — A few of the siliceous organisms found floating 

 in the surface and subsurface waters of the ocean. Figs. 

 1-8 represent Diatoms, and Figs. 9-17 Radiolaria [drawn 

 to different scales]. 



Plate VIII. — A few of the mollusoa with calcareous shells 

 found floating in the surface and subsurface waters of 

 the ocean. Figs. 1-5 and 7-14 are Pteropods, Figs. 6 

 a-nd 16 are Heteropods, and Fig. 15 is a Gasteropod [drawn 

 to different scales]. The dead shells of these organisms 

 especially predominate in pteropod ooze. 



Plate IX. — The principal forms of pelagic Foraminifera 

 found floating in the surface and subsurface waters of 

 the ocean, the dead shells of which predominate in the 

 pelagic deposits, especially globigerina ooze. 



Plate X. — A few of the numerous forms of bottom-living 

 Foraminifera (benthos) with calcareous shells (in contrast 

 to Plate IX.). These forms are easily distinguished 

 from the pelagic shells in the bottom-deposits. 



Plate XI. — Map showing the distribution of the five types 

 of pelagic deposits (pteropod ooze, globigerina ooze, 

 diatom ooze, radiolarian ooze, and red clay) ; the areas 

 occupied by the five types of terrigenous deposits (blue 

 mud, red mud, green mud, volcanic mud, and coral 

 mud) are left uncoloured. 



Plate XII. — Organic and inorganic materials from the red 

 clays, including teeth of sharks, earbones and beaks of 

 whales, crystals of phillipsite formed in situ, and small 

 magnetic spherules derived from extra-terrestrial sources. 



