208 THE MOLLUSK FISHERIES 



are waste, and covered for the most part with eel grass. Other sections 

 elsewhere are likewise waste for various causes, and are to be excluded 

 as unprofitable or barren; yet the total available area remaining after 

 making these deductions exceeds 350 acres. This is the theoretical con- 

 dition, the real condition is far otherwise: 20 acres at the most 

 yield clams, and of these only 10 acres produce them in marketable 

 quantities. 



The explanation of these conditions is interesting. In the winter 

 the ice and the force of storms tear out great pieces of the tough marsh 

 surf, and the tides sweep them down the harbor. Some of these huge 

 masses are torn to pieces and washed away, others find lodgment on the 

 broad surface of some tidal flat; these, becoming stationary, accumulate 

 sediment; the grass grows upon them through the summer, and grad- 

 ually a little island is formed. Surrounding these islands and often- 

 times growing over their entire surface, bedded in among the roots of 

 the marsh grass, we find a very thick set of clams. In short, all the 

 digging of any kind is in the immediate vicinity of these islands. 



The deductions to be made from these facts are apparently simple. 

 In the spawning season, when the microscopic clam larva} are in their 

 floating stage, they are carried here and there by the currents. Later, 

 when they tend normally to settle in some fertile tract of flat, they are 

 prevented from so doing by reason of the remarkable swiftness of the 

 tides, which sweep strongly over the broad, smooth flats, and give 

 the little clams no opportunity of lodgment. Only in the firm thatch of 

 low-lying islands can they find anything to cling to, and here, with 

 their slender byssus threads attached to unyielding grass or roots, they 

 are able to withstand the wash of the current. Thus the clams are 

 gathered in great numbers in these natural collectors, later are washed 

 on the neighboring flat, and finally a little colony grows up about every 

 island of this sort. 



That this is actually what happens is largely borne out both by 

 observation and facts. It makes little difference where these islands 

 are located; clams grow nearby, while all about may stretch smooth, 

 hard flats, perfectly adapted for clams, yet altogether barren. In view 

 of the somewhat incomplete investigations made in this region, it is per- 

 haps too sweeping to point out any single factor as the sole cause for 

 these waste areas ; but undoubtedly the swift tides and smooth, hard flats, 

 which offer no resting place for the young larvas, constitute the main 

 causes. 



Another odd circumstance in connection with the Barnstable clam in- 

 dustry is the local regulations which control the industry. Almost all 

 digging is carried on in the winter, as a local by-law forbids the digging 

 of clams in summer in any quantity exceeding 6 bushels per week for 

 family use. This somewhat curious by-law is designed wholly for the 

 benefit of the majority of the clammers, and .to give them employment 

 in that season of the year when work is most difficult to obtain. While 



