178 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
ON THE STRUCTURE AND Lirse-HIstTory oF THE CoMMON 
COCKLE, WITH AN APPENDIX ON THE LANCASHIRE 
CocKLE FISHERIES, with Pls. I—VI. and Map. 
(J. JOHNSTONE.) 
[Nott :— This investigation into the structure of the 
cockle was carried out mainly in the Fisheries Labora- 
tory at University College, Liverpool; but in part also 
at the Sea-Fish Hatchery at Piel—which was found 
most convenient for the study of living specimens. 
Most of the material used was obtained from the cockle 
beds in the Mersey estuary, and was collected and sent 
to the Laboratory by Mr. G. Eccles, chief fishery 
officer at New Brighton. Specimens were also sent 
by Mr. Andrew Scotié from the Baicliff beds and those 
in the immediate neighbourhood of Piel.] 
THE edible cockle (Cardiwm edule) is by far the commonest 
member of the genus Cardiwm, a group of eulamelli- 
branchiate Mollusca having a world-wide distribution and 
containing a great number (about 200) of species. The 
- number of British species is, however, limited to ten, 
most of which (C. echinatwm, C. fasciatum, C. edule, C. 
muumum, C. norvegicum, C. nodosum) are recorded as 
being present in the Irish Sea; of these the only abundant 
species is C. edule; C. norvegicum (Levicardium) is fairly 
common, the others being only occasionally found. ‘The 
different species seem to have a fairly well-marked bathy- 
metrical range, but C.edule is found from between tide 
marks out to 13860 fathoms. Here and over the greater 
part of Europe C. edule is the only species of any economic 
importance; in Jersey, however, C. norvegicum is used for 
food, and in the Mediterranean various other species are 
eaten. 
The edible cockle is gregarious all along the coast line 
where suitable bottoms exist, but the great cockling beds 
