MUSSEL AND COCKLE. 53 



attached; the canal is then opened through its whole length 

 to free the thread, and closing again is ready for another 

 casting; as if conscious how much depends upon the security 

 of his lines, the animal tries every one after he has fixed 

 it by swinging itself round so as to put the threads fully on 

 the stretch; when once they are all firmly fixed, it seerns to 

 have no power of disengaging itself from them; the liquid 

 matter out of which they are formed, is so very glutinous, 

 or glue-like, as to attach itself firmly to the smoothest bodies. 

 The process of producing it is a slow one, as it does not ap- 

 pear that the Pinna can form more than four or five in the 

 course of twenty-four hours. AVhen the animal is disturbed 

 in its operations, it sometimes forms these threads too hastily; 

 they are then more slender than those produced at leisure, 

 and, of a consequence, weaker. On some parts of the Med- 

 iterranean coast, as in Sicily, gloves and other articles have 

 been manufactured from the threads of this mollusk; they 

 resemble very fine silk in appearance. 



The foot of the Cockle, of which we here give a figure, is 

 commonly employed in scooping out the 

 mud or sand, beneath which it conceals 

 itself; this useful limb assumes the form 

 of a shovel, hook, or any other instru- 

 ment necessary for the purpose; it ap- 

 pears to be a mass of muscular fibres, 

 and to possess great power. As a boat- 

 man in shallow water sends his vessel 



along by pushing against the bottom with his boat-hook, 

 precisely so does 3Ir. Cardium travel; he doubles up his foot 

 into a club, and by an energetic use of it as a propeller, 

 makes considerable headway along the surface of the soft sand 

 beneath the waters. In this way, too, some members of the 

 genus sole7i force their way through the sand; while those 

 called Tellina spring to a considerable distance, by first folding 

 the foot into a small compass, and then suddenly expanding 

 it, closing the shell at the same time with a loud snap; so 

 that you see these sober-looking mollusks are sometimes fro- 

 licksome fellows; this is an enforcement of the lesson, judge 

 not by appearances. 



Some of the species, both of the Mussel and Cockle families, 



