THE ECONOMIC MOLLUSCA OF ACADIA. 99 



and it may then be seen that tlie entering water must bathe the four 

 great, flat gills as it passes downwards towards the mouth. These gills 

 subserve the same function as do those of fishes, for in them the blood 

 of the animal receives its needful oxygen and gives off its useless gases. 

 Near the extreme anterior (though lower) end, guarded by four long 

 ear-like flaps, is the minute mouth, and into it are guided by the flaps 

 the minute animals, plants and Crustacea upon which it feeds. The 

 water, now robbed of its oxygen and food materials, passes along the 

 back or hinge side, taking up useless matters given off by the animal 

 and passes out through the other tube. These tubes have the power of 

 great extension, so that when their owner is safe deep in its burrow, it 

 can push them up to the surface and get clear, pure water At low 

 water, when the flats are exposed, it retains water enough to last until 

 the tide covers it again, when, doubtless hungry enough, it keeps up an 

 active in and out circulation of water. If it is incautious enough to 

 come to the surface, it is likely to be snapped up by some fish, for 

 many of this tribe dearly love the Clam. It also lives under many 

 fathoms of water, where its habits are probably the same, Its time of 

 reproduction has not been studied carefully in our waters, but probably 

 does not differ greatly from that of the same species farther south, 

 Mr, Ryder (see paper referred to below) finds that they give out their 

 eggs from the tenth of September to the middle of October. The 

 young are without shells and can swim freely about for a time, a 

 provision to allow them to be removed from the vicinity of their 

 parents, and so to prevent overcrowding. They soon settle to a sand 

 or mud bottom and as they develop the shell, burrow beneath the 

 surface. They grow to a length of from one to two inches in seven 

 months, these lengths being exclusive of the tubes. The artificial 

 raising of the young is considered very diflicuU, though they may be 

 transplanted readily to new beds. 



Economics. This species has two very important uses — 

 as human food and as bait in the fisheries. For the latter 

 purpose it is very extensively used in Acadia, and also in the 

 United States. Exact statistics of the quantity used for bait 

 alone are wanting in the latter country, and the Dominion 

 Fishery Eeturns probably give but an imperfect idea of the 

 quantity used in the former. Nova Scotia is the only one of 

 the Maritime Provinces which gives figures in the reports, 

 which for the years from 1884 to 1887 are as follows: 



1884 750 barrels @ $7= $5,250 



