83 
parts of our fish nurseries to shrimping. We desire to 
know not merely the statistics of the ‘‘ catch,” 7.e., the 
fish and shrimps in each haul, but also the relative 
abundance of invertebrate (food) animals on closed and 
open grounds, and full details as to their kinds and 
abundance, their life-histories and changes throughout the 
year, and their food, for comparison with that of the 
shrimps and fishes. 
Furthermore, we obviously require to have full infor- 
mation in regard to the structure and habits of both the 
shrimp and the fishes throughout their life-histories before 
we can be sure that any alteration in relative numbers will 
be permanent. We know a good deal about such matters 
already, either in our own seas or in other parts of the 
world. Professor J. S. Kingsley,* in America, has made 
us acquainted with the development of the early stages of 
the shrimp (Crangon vulgaris), and Dr. Ehrenbaum has 
given us much information as to the structure and life- 
history of the shrimp at Heligoland.+ All that is a help, 
but still there are many local details that must be worked 
up on our own ground. We must know exactly where 
and when the various stages occur, and in what abundance, 
and in what association. 
Then turning to the little fishes, if we take the plaice 
again as an example, Mr. Johnstone has given, in the 
appendix to our own Report for 1901 (No. X., p. 211), a 
summary of what is known as to the development on our 
coasts, and the habits and food at the various stages. If, 
however, we take the young sole—a very valuable, and 
frequently abundant, constituent of the fauna on the 
shrimping grounds—much less is known, and the exact 
* Bulletin of the Hssex Institute, 1887 and 1889. 
+ Naturgeschichte von Crangon vulgaris, 1890. 
