138 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
the estuary of the Dee, as well as elsewhere, they 
settle down after the free swimming stages in such 
profusion that the rocks, seaweeds, zoophytes, and any 
other relatively solid objects are blackened with the 
minute shells. Practically none of these grow to maturity. 
Some have settled down on unsuitable objects, many are 
crowded out by their neighbours, the star-fishes eat 
enormous quantities, but the greater number on account 
of their not having been able to obtain a firm point of 
attachment for their byssus threads are swept off, by the 
waves, in sheets when they are from } to $ an inch in length 
and are rolled about in masses on the sands till they decay. 
This miserable waste could probably be prevented by 
providing fixed objects for the mussels to attach to, and by 
taking care of the young beds when once they were estab- 
lished, by thinning out from some places and laying down 
in others, by keeping carts, &c., from going over the beds 
and crushing the animals, and finally by preventing the 
mussels from being collected until they are of a fair 
size—say 24 inches in length. 
We have examined a large number of mussels from 
various parts of the district in the laboratory in order to 
determine their food, spawning time, and anything else 
possible in regard to their conditions of existence. The 
stomachs generally contained plenty of food, consisting 
entirely of microscopic matters, such as the spores of 
Algze, very many Diatoms of different kinds, fragments 
of Algze and vegetable debris, Sponge spicules, Foramin- 
ifera, remains of Copepoda and of Nauplei, and fragments 
of Zoophytes. . 
A well established mussel bed usually supports large 
numbers of microscopic lowly plants and animals, which 
find shelter in the crevices between the mussels, and which 
supply with food not only the molluscs but also the young 
fish and the food of the fish of the neighbourhood. 
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