CONSTRUCTION OF THE BYSSUS. 173 



fixed to the glass. This object being light in 

 colour, had a pretty effect when contrasted with the 

 rich brown tint of the spinner. Shortly afterwards 

 the foot rolled over and withdrew into the shell, 

 leaving behind it the silken thread which had just 

 deen spun. The ' little mouth/ above described, was, 

 if I may so term it, the mould in which the end of 

 the thread was cast. 



In the course of two hours a bundle of byssus 

 threads, sixteen in number, were produced by this 

 industrious little labourer. 



Having thus seen that the foot is useful to the 

 Mussel as an instrument of progression before the 

 beard is formed, let me now endeavour to show that 

 it is, at times, of equal service for the same object, 

 after, and when the mollusc is anchored thereby to 

 any particular spot. 



When we remember that this anchorage is formed 

 of a harp-like set of strings, amounting to ten or 

 even a hundred in number, it does seem an almost 

 incredible fact that the Mytilus is enabled to change 

 its station, even when living in single blessedness. 



To see a Mussel ' flit/ is a sight one may often 

 watch and wait for without success. On the other 

 hand, when least expected, the self-willed mollusc 

 may commence operations. When about to take up 

 a new home, the animal shaves off its beard entirely, 

 or in more scientific language, 'rejects its byssus' 

 altogether. In order to excite the locomotive in- 



