OF MASSACHUSETTS. 61 



large as 10 millimeters have this habit of floating, and scallops of 6 

 millimeters are often found with tentacles widely spread out. The 

 reverse position of the animal, the right or lower valve being uppermost, 

 is not so unnatural as may seem at first, as it can be likened to the crawl- 

 ing of a fly on the ceiling. The surface of the water acts as a wall 

 upon which the scallop, with its extended foot, can rest. Peeten and 

 Anomia have been observed apparently crawling, right valve up, on the 

 surface of the water in the same manner as on the bottom, only in a 

 reversed position, evidently in a similar manner to snails, by mucous 

 secretion. 



In the case of the small scallops, the tentacles, which appear to sup- 

 port the larger scallops, are not essential for floating. Very small disso- 

 conch scallops, before the formation of tentacles, have the floating 

 habit, and do not depend, therefore, on the tentacles to support them. 

 The habit of floating is useful in that it probably allows the scallop 

 the opportunity to get a better supply of oxygen, and to be carried from 

 one locality to another or from one stalk of eel grass to the next by the 

 current. 



MiGEATION. 



Many remarkable stories concerning the movement and migratory 

 habits of the common shallow-water scallop have long circulated among 

 the fishermen. Several writers have described schools of scallops iu 

 the act of skipping and swimming over the surface of the water, and 

 have attributed to this species the migratory powers of fish. Scallops 

 are reported to traverse many miles, passing from one part of the coast 

 to another, continually on the move. Unfortunately, these stories have 

 arisen from incomplete observations, which, supplemented by the use 

 of the imagination, have credited the scallop with powers it never 

 possessed. Indeed, so much has been said concerning the swimming 

 powers of the scallop that people have come to believe that the scallop 

 should be considered as a migratory fish. 



While the basis of these reports is correct, there has been much 

 exaggeration. The scallop has the power of migration only in a limited 

 sense, and although capable of swimming never traverses far. In a 

 small bay or haxbor it is possible for the scallop to move to various 

 parts, especially if there is a strong current, but extended and definite 

 movements never occur. Swimming is a frequent diversion of the scal- 

 lop, which, after lying quietly on the bottom, suddenly takes a slanting 

 " shoot " through the water. The scallop is not built for continuous 

 traveling, as it seems to need periods of rest between each flight. The 

 average distance covered in a single movement is about 10 feet, while 

 often it is much less. The longest flight ever noticed by the writer 

 was about 25 fget, which is an exceptionally long distance for the 

 scallop to traverse at one time. Occasionally a series follow in quick 



