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THE AMERICAN MUSEUM JOURNAL 



free-swimming mussel embryos that 

 fastened themselves to the pebbles and 

 grains of sand at the mouth of the pond. 

 As if by magic the broad expanse of 

 white desert sand was covered with a 

 blue-black carpet of sea mussels in a 

 single season. I counted as many as 

 one thousand of these shellfish to the 

 square yard and estimated that there 

 were approximately ten thousand bushels 

 to the acre. 



object. This movement is followed by a 

 relaxation of the circular muscles and 

 the contraction of a set of longitudinal 

 muscles that result in drawing the ani- 

 mal forward. Young mussels are much 

 more active in moving about than are 

 adults. Some specimens about a quarter 

 of an inch long were lined up for a race 

 over a measured piece of ground and 

 were observed to make a speed record 

 of one inch per minute. The young 





River bottom at Sandwich, Massachusetts, wlien exposed at low tide. Female mussels lay annually some teD 

 to fifteen million eggs each. The minute free-swimming embryos may enter a salt water stream, attach themselves 

 to the rocks of the bottom, and in a single season convert the atoms of dead organic matter of the river mud and 

 the numberless millions of microscopically small plants and animals of this mud into a vast bulk of flesh food 



The ability of the sea mussel to exist 

 tinder such crowded conditions depends 

 upon its power of movement, means of 

 anchoring itself firmly, and the wonder- 

 ful efficiency with which it is capable of 

 collecting food. Locomotion is accom- 

 plished by means of a muscular strap- 

 shaped foot equipped with a sucker on 

 the end. By contraction of a set of 

 circular muscles the foot is thrust out 

 and the sucker attached to some solid 



shellfish can creep up perpendicular 

 surfaces, such as are presented by rocks 

 and wharf piles, as readily as they move 

 on a horizontal plane. Their power 

 of locomotion under difficult conditions 

 is sufficient moreover to enable them to 

 do greater feats than to climb up vertical 

 walls, for on reaching the surface of the 

 water when it is perfectly quiet I have 

 seen them, like the pond snail, creep out 

 on the under side of the superficial film. 



