130 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



A CONTRIBUTION TO THE ECOLOGY OF SOME 

 COCKLE BEDS. 



By C. L. WALTON, M.Sc. 

 (Department of Zoology, University College of North Wales, 



Bangor). 



The following notes are the result of observations made 

 from time to time on various cockle beds on the west coast of 

 England and Wales, between September, 1912 and September, 

 1919. The work has been much interrupted and is far from 

 being complete, but it is hoped that the investigations may 

 proceed further in due course. The present series of observa- 

 tions were gathered from Milford Haven to Morecambe Bay, 

 during the progress of work under grants from the Board of 

 Agriculture and Fisheries to Aberystwyth University in the 

 first instance, and latterly from the Lancashire and Western 

 Sea-Fisheries Laboratory, Liverpool University. All the 

 beds mentioned (with the exception of Milford Haven) lie 

 within the Lancashire and Western Sea-Fisheries area, while 

 those most thoroughly examined are situated in the Dyfi 

 Estuary. 



I. Life Conditions as affecting the Fauna. 



General situation of Cockle Beds. 



The edible cockle (C. edule) and its accompanying fauna 

 occurs in many places on the coast and under very varying 

 conditions, but it cannot exist in large numbers unless the 

 following conditions are fulfilled : — 



1. An expanse of sand or sandy mud. 



I have found cockles in almost pure mud and even in 

 muddy gravel, in sufficient numbers to be picked for sale. In 

 the former case they were well grown and numerous and 



