SEA FISHEEIES LABOBATOBY. 143 



SHELL-FISH. 



I. Mussels. 



During the year 523 mussels (Mytilus edulis) have been 

 examined with the view of finding out the time of spawn- 

 ing and also the food of this important shell-fish. So far 

 the result of this examination seems to show that the 

 food of the mussel consists of Diatoms, Spores of Algae, 

 Vegetable debris, Foraminifera, and remains of Copepoda, 

 all of which are no doubt brought within reach of the 

 mussel's ciliary currents by the motion of the surrounding 

 sea water ; the variety in the food will therefore depend to 

 a very large extent upon what is the general fauna of the 

 mussel bed. As the food is, however, comparatively well 

 known now, our attention was more especially directed 

 to the determination of the spawning period, and as far as 

 the year's results go they appear to show that the mussel 

 reaches maturity about the middle of May, and that the 

 spawning period lasts to the middle of July. There seem 

 to be a few exceptional cases, but the majority of the 

 mussels on the Lancashire coast have probably finished 

 spawning by the time stated. 



In a report in 1886 by Mr. John Wilson, B.Sc, on the 

 development of the common mussel, published in the 

 appendix to the Fourth Annual Report of the Fishery 

 Board for Scotland, p. 218, it is stated that "Professor 

 M'Intosh found that in general the mussels reached full 

 reproductive maturity in April ; thereafter the ova and 

 spermatozoa gradually disappeared from the mantle, until 

 in July those he examined were spent." 



The following list gives the results of the examination 

 of the samples sent to us. 



Morecambe. 



Jan. 24 



11 fish 



2-2;| inch. 



3 female ^l i 



8 male j^arly ripe. 



-1 Empty, 7 Spores, 

 Diatoms and Veg- 

 etable debris. 



