MUSSEL AXD COCKLE. 53 



attached; the canal is then opened through its wliole 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 ever}^ 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 seems to 

 have no power of disengaging itself from them; the liquid 

 matter out of which tlioy 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. When the afiimal 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 fi'om 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 an}^ 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, 

 preciselj^ so does Mr. 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 membere of the 

 genus solen force their waj^ through the sand; while those 

 called Telling 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 5'ou 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, 



