30 



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 J 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 2j 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 

 Algse, very many Diatoms of different kinds, fragments 

 of Algte 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. 



