142 Shell Life 



siphons are separate throuohout, with white fila- 

 ments along their sides. The white or yellow foot 

 is proportionately small, though long, and ends 

 in a thin flat point. It occurs in great numbers 

 on all our sandy shores from low water to about 5 

 fathoms ; and a smaller, thinner variety extends 

 up estuaries into brackish water, as, for example, 

 up the Thames as far as Gravesend. It is said to 

 occasionally depart from its burrowing habit and to 

 take to climbing up submerged posts, spinning a 

 byssus to aid it. The raking in of Cockles for food 

 and bait forms no inconsiderable item of what is 

 comprehensively called the fishing industry. The 

 Least Cockle (C. minhnum) might at first sight be 

 taken for a young example of the last mentioned. It 

 has a roundish-oval, thin, glossy white shell, crossed 

 by 28 or 30 flattened, radiating ribs, which bear 

 minute arched scales. It is subject to little or no 

 variation, but individuals that have lived in coarse 

 sand may be found with the ribs cleaned off by 

 attrition, whereas those found in muddy sand have 

 the ribs beautifully sharp and fresh. It is not widely 

 distributed; but it has been found off the west of 

 Scotland, Shetland, Ireland, Isle of Man, Scilly, 

 Lundy, the Smalls, and West Orkneys, burrowing in 

 fine sand at depths between 5 and 100 fathoms. 



The Smooth Cockle (C. norvegic iim) differs from 

 all the others in appearance, not only by reason of 

 its smoothness, but also of its shape. The shell is 

 distinctly triangular in outline, wedge-shaped when 

 viewed from the ends, and crossed by about 40 ribs, 

 which are all but obliterated owing to their lowness 

 and the shallowness of the intervening grooves. The 



