42 MUSSEL CULTURE 



peculiarity of possessing a byssus gland which 

 secretes the 'beard' for the attachment of the 

 mollusc. 



On opening a mussel and folding back the 

 shells, the body is seen to consist roughly of 

 the two flaps of the mantle attached to, and 

 filling, the two valves of the shell, and a more 

 or less compact portion in the centre. The thin 

 or tapering end is described as anterior, the 

 thick and more bulging end behind the hinge 

 as posterior. The mouth is at the anterior end, 

 and between the mouth and the beard is the foot, 

 the shape of which varies very much according to 

 the extent to which it is protruded or retracted. 



Just inside the edge of the mantle, at the an- 

 terior end, will be found two pairs of small loose 

 flaps, an outer and an inner, on each side of the 

 middle line. These are termed the labial palps, 

 and the exact position of the mouth may at once 

 be determined by examining their anterior ends. 



Extending from between the inner and outer 

 palps, on each side, to the posterior end of the 

 animal, the gills may be distinguished ; a pair 

 on each side of the middle line. Each pair, 

 when the mussel is in its normal position, pro- 

 jects freely in the cavity formed by the surround- 



