114 The Scottish Naturalist. 



varying in size from different localities, caused by local differences 

 in the surroundings. . 



Mr. Farquharson believes that mussels may reach quite a 

 patriarchal age, and that they may even live hundreds of years. 

 They have been found deep in the gravel, even, in railway excava- 

 tions, at a depth of twenty feet, to which depth it has been sup- 

 posed that they have burrowed, though something must be allowed 

 for subsequent deposition of sediment. Mr. Farquharson some 

 years ago tried an experiment. He selected about a thousand 

 shells ; and from each of these he chipped off a piece of the 

 shell, and thereafter replaced them in the stream. I guess this 

 operation has something to do with the attempt to make them 

 produce pearls : but on this subject I must reveal no secrets. 

 About eighteen years afterwards he found that these mussels had 

 grown only one inch, so that they might still be said to be in their 

 teens. On this calculation it would require a hundred and forty- 

 four years for a mussel to reach its full size, since the average 

 length of a mature shell is eight inches. 



A full grown mussel can protrude itself to a couple of inches 

 from the opening of its shell. When so protruded the eyes may 

 be seen peeping out. The excreta are green like the contents of 

 the stomach, which apparently undergo little change in digestion. 

 The stomach can contain about an ounce of food at a time. 



It is sometimes difficult to haul the creature out of its burrow : 

 but the difficulty is lessened when the burrow is in loose 

 gravel. 



In a mussel-bed shells of all ages and sizes are brought up by 

 the drag-net, which is often used in fishing for them. The ques- 

 tion of the mortality of the creatures has been in passing touched 

 upon already, in the reference to the great age attained by them. 

 We are taught by statistics that the average life of the human 

 race is thirty-five years ; but Mr. Farquharson's experience makes 

 him conclude that the mussels show a much less mortality than 

 mankind. He has examined myriads of mussels in a year, yet in 

 all his long experience he has found only two or three dead ones. 

 This goes to show that if the mussel is not intellectual, it has at 

 least the possession of long life, accompanied by all the pleasures 

 of the gratification of its appetites. 



They are able to move from place to place ; though what the 

 motive may be is very doubtful. One may trace on the muddy 



