SEA-FISHEKIES LABORATORY 



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from Sandy Haven (Milford Haven) where a very limited bed 

 exists, while another has been reported (and several examples 

 sent to me) from Solva, also on the S. Pembrokeshire coast. 

 In the case of Sandy Haven the largest example obtained 

 measured 50 mm. in length, and the number of growth marks 

 was seven. Two from Solva were both 55 mm. in length, 

 and showed seven and eight grooves respectively. One Barra 

 cockle I have seen showed no less than 10 ! 



The distribution of ages within a square foot of cockle 

 bed is shown by the following examples, from Ynyslas, Dyfi 

 Estuary. 



Table II. 



Ribs of Shell. 



An examination of 400 shells (100 from Lavan Sands, 

 nr. Bangor, N. Wales, and 300 from Bardsea, Morecambe Bay) 

 shows distinctly that there is no correlation between the 

 number of ribs present and age and size of shell. In the 

 smallest cockles examined (group 0.98 to 1.50 cm. in dorso- 

 ventral diameter) the number of ribs varied in exactly the 

 same degree as in the largest (group 3.50 to 4.11 cm.). 



The number of ribs ranged from 20 to 27; in other 

 words, the number of ribs remains constant throughout life. 



During the enumeration of the ribs, difficulty was 

 encountered with regard to variability in the areas known as 



