108 Part L1I.—Twenty-jirst Annual Report 
EXPLANATION OF PLATE I. 
Chart of ‘the North Sea, showing the areas of different depths—(1) up to 20, 
(2) between 20 and 30, (3) from 30 to 50, (4) from 50 to 100 fathoms, and (8) 
over 100 fathoms. 
Hg. = Herring ; M. = Mackerel; L. = Lythe; 8S. = Sturgeon. 
The black spots show the localities where special trawlings have been made, 
as follows :— 
I,—-August 31, September 4, 1900; IT.—16-19 October, 1900; III.—May 15, 
1901 ; 1V.—May 16, 1901 ; V.—May 17, 1901; VI.—May 19-22, 1901; 
VII.—December 11, 1901; VIII.—March 10, 1902; IX.—May 23-28, 
1902; X.—-May, June, 1902. 
