EXPLANATION OF THE PLATES. 



PI. I. The map of the North Polar Sea gives the position of Stations where bottom- 

 samples were taken during the Expedition. 



Pis. II & III. The Curves illustrate the quantities and different sizes of the grains in the 

 samples of bottom-deposits. The area delimited by the upper Curve represents the 

 whole of the sample. The lower curve represents the actual mineral grains (mostly 

 Quartz). The area between the two curves therefore represents the Clay. 

 For further explanation see also pp. 22—27. 



