4 
The results have been reduced to a common standard — the catch 
per one hour's trawling. They demonstrate that the population of 
flat fish improved steadily from 1892 to 1903, since when there has 
been a decline. The above examination with reference to season 
shows that the increase has been to a large extent brought about by 
the late summer immigration. 
An interesting change with regard to the food of the fish caught 
at the trawling experiments has taken place, sandeels having 
replaced common molluscan and crustacean forms, which latter also 
have evidently diminished in numbers. 
At the trawling experiments of 1905, 372 flat fish were marked 
and liberated, principally dab, flounder and turbot. The total 
number which have been labelled since 1903 is 1,321. It is now 
evident that plaice remain within the district until at least about 
11^ or 12 inches in length, when they are about 5 years old, and 
that the migration from the district, with approaching maturity, 
may be to a great distance. The dab and flounder show a tendency 
to migrate to the south, but this only refers to a few examples, the 
large majority evidently being stationary. 
The trawling and migration experiments have furnished inform- 
ation with regard to the growth of the flat fish. 
A brief account is given of the modern decline in the inshore 
white fisheries, and of the growth of North Shields. 
It is concluded that the improvement in flat fish shown by the 
experiments, is due to the protection afforded to the resident young 
population by the prohibition of trawling within the district. 

A further consideration of the crab and lobster fisheries of 
Northumberland demonstrates that the protection of such fisheries 
by reasonable legislation may be depended upon as a means of 
improvement. The experiments on the migration of the crab 
confirm the previous results that the hardening females migrate into 
Scottish waters. 
Miss M. Y. Lebour, B.Sc, gives a paper on the Trematodes which 
have been met with in the course of an examination of Mollusca, 
and especially of the common mussel, in connection with a research 
on the mussel beds of Northumberland. 
