"SHELL-FISH." 189 



second syphon. The length and form of these syphons differ 

 in distinct species, but each kind is pretty true to its own type, 

 and, consequently, the impression that it makes on the interior 

 of the shell, taken in conjunction with the muscular and pallial 

 impressions and the hinge-teeth, are a certain guide to the 

 discrimination of species. 



These are matters that are essential to one's knowledge of 

 the mollusca, and they must be learnt ; but the few species we 

 shall be able to mention in this chapter will be indicated more 

 by their external shape, marks, and colouring. When so 

 identified, the reader should strengthen his knowledge by a 

 practical study of these internal impressions, and the charac- 

 ters of hinge and teeth. 



This Spiny Cockle, or Red Nose (Cardium aculeatuni], is 

 not the Vulgar Cockle (C. edule), although it is much sought 

 for food on its native Devonshire coasts. It is a very much 

 larger species than the last-named, and gets its name of Red 

 Nose from the brilliant hue of its long strong foot, which is at 

 once a burrowing instrument and a leaping pole. By pushing 

 its pointed end down into the sand, and then bending it into a 

 hook, it can, by contracting the foot, pull the thick prickly 

 shell down after it. On the other hand, by pressing its bent 

 tip against some unyielding substance, it can use it as a spring, 

 which shall suddenly send the shell flying through the water 

 to some considerable distance. The Spiny Cockle is a crea- 

 ture of clean, sandy beaches, where it may be found at low- 

 water, but only on the Devonshire coast. 



The Common Cockle (C. edule] is very much smaller, its 

 shell free from prickles, and marked merely with bold rounded 

 ridges. It is more likely to be found where the sands are not 

 wholly of sand, but contain a liberal admixture of mud. On 

 some of our coasts it is exceedingly abundant, and in times 

 of famine has saved populations from starvation. It is cer- 

 tainly on record that the people of the Isle of Barra, in the 

 Hebrides, have been thus preserved many years ago, when all 



