35 



time to time in the shallow waters of our district require 

 further investigation. At times Shrimps are very scarce, 

 having apparently either migrated to deeper water or 

 buried themselves in the sand.* This seems to be largely 

 the result of temperature variations. Periodic observations 

 at fixed stations, the Shrimp trawl being down for the 

 same time, and at the same state of the tide, say once a 

 week, should, supplemented by our work in the laboratory, 

 give us a good deal of information in regard to the life- 

 history of the Shrimp throughout the year. 



I have suggested above, in connection with the des- 

 truction of immature fish, that Shrimp culture might be 

 carried on in our estuaries. At any rate the matter ought 

 to be tried on a small scale experimentally. A sheltered 

 creek or bend in one of the estuaries should be closed in 

 by stakes and wattling, like a fishing weir, so as to keep 

 out Skates, Codling, Crabs, and other enemies. This 

 preserve could then be stocked with Shrimps — which 

 might be fed with any fish refuse — and if it were found 

 that the young stages when hatched out could be kept 

 inside the enclosure and reared, the probability is that in 

 the absence of enemies and with abundance of food the 

 numbers would increase very greatly. 



Edible Mollusca. 

 The edible mollusca of chief importance here are the 

 Cockle. (Gardium edule), and the Mussel (Mytilus eclalLs), 

 and a certain amount of work has been done on both of 

 these shell-fish in the laboratory. 



The Cockle. 

 In examining for food, specimens sent by the bailiffs the 

 first thing noticed was the very large proportion of indi- 

 viduals in which the stomach was quite empty, the reason 

 * See Trans. Li verpool Biological Society, vol. V. p, 49 ; and vol. VI. p. '4~. 



