188 SHELLS AND MOLLUSCOUS ANIMALS. 



times indigestible, and probably the ordinary cases 

 of illness are sufficiently accounted for by the fact, 

 that the persons rendered ill by them were in a 

 state of health little fitted for the digestion of food 

 of this nature ; but this will not account for every 

 case. The best mussels are procured from Ham- 

 bleton, a village in Lancashire, at which place, 

 having been taken from the sea, they are put in 

 the river Weir, where the tide can reach them, 

 and where they become plump and of a delicate 

 flavour. 



The byssus, or silky beard, by which the mussel 

 moors itself to the stone, is a familiar object of 

 our sea rocks. It is, in its nature, like the silk of 

 the silkworm, or the silvery thread woven by the 

 spider, and it exudes, in a glutinous state, from an 

 organ at the base of the foot. A groove extends 

 along this part of the foot, the sides of which fold 

 over to form the little canal, along which the 

 glutinous substance runs, which shortly acquires 

 the consistence of a silky thread. The animal 

 then protrudes its foot, and fastens the thread to 

 the rock ; then a fresh thread is again formed in 

 this little groove, until the mussel has made enough 

 for his moorings. The animal can spin many 

 hundreds of these strong and durable silken cables, 

 but it does not waste its powers, but skilfully 

 adapts their numbers to its condition. When 

 attached to a rock over which the sea-wave rushes 

 wildly, it spins a strong and many-threaded cable ; 

 but when lying on some sheltered spot, where its 

 dwelling is in no danger of being torn away, it 

 spins but few. Daniel, in his " Rural Sports," 

 mentions an instance in which the mooring of the 

 mussel was useful to effect a purpose which human 



