GIANT SCALLOP FISHEEY OF MAINE. 
317 
able rate of growth, in P. irradians, which has been more thoroughly studied thau auy 
other species in this country. The basis for the belief that the scallop attains the 
proximate limit of size in a few seasons is that frequently, in the spring, when the fish- 
ermen visit a ground on which they have worked the previous fall, the scallops are found 
to be so small that it hardly pays to take them, while in the succeeding autumn and 
winter they are as large as in the previous year. 
Mr. Heath states that the fishermen of Mount Desert Island find the scallops that 
are 4 or 5 inches iu diameter to be the cleanest, brightest, and liveliest. Those of 8 
inches look old, their shells are dingy, rough, ami brittle, and are apt to be more or less 
honeycombed by the chambers of the boring-sponge. 
The duration of the life of a scallop after reaching maturity is thought to be quite 
brief. Some fishermen think that it dies within one year, and it seems probable that 
the life term is normally not more than 5 or 6 years. 
Mr. Benedict, as the result of observations off the Massachusetts coast, thinks 
that exceptionally at least the scallop attains great age. Mr. Yogell, of Oastine, has 
also seen specimens that were so large, thick, and tough that he estimated their age 
at not less than 15 years. 
Unlike many mollusks, the scallop has the interesting and useful accomplishment of 
free locomotion in the water. By means of the powerful adductor muscle the animal 
is able to rapidly close its valves and to forcibly throw out the water between them. 
The resistance thus arising tends to swiftly propel the mollusk in the opiiosite direc- 
tion by a series of short jerks. Few fishermen are aware of this phenomenon and 
few persons have ever witnessed it, owing to the depth at which the swimming opera- 
tions usually occur. The sight of a school of scallops moving iu unison through the 
water is said to be a very striking one. The small shallow- water species ( P. irradians) 
is frequently seen swimming, or “dancing,” as the sliding motion is termed; but only 
here and there on the Maine coast are fishermen found who have actually observed 
the habit iu the giant scallop. 
This faculty of the scallop is probably exercised when iu search of new feeding- 
grounds or of water of a more congenial temperature. It is a matter of personal 
experience with the fishermen of certain localities to find that the scallop beds shift 
from time to time, although these wholesale migrations are not nearly so extensive as 
might be supposed and in some localities are unknown, although not for that reason 
alone necessarily absent. Inquiry in the vicinity of Mount Desert Island failed to 
elicit the knowledge of any perceptible change in the position of the beds in that 
vicinity, which have been operated from the same positions since the establishment of 
the fishery. Mr. Vogell, speaking of the beds in the vicinity of Oastine, says they do 
sometimes shift, and that there will at times be good fishing on a ground which a week 
before was destitute of scallops. He assigns the search for food as the cause of the 
movements. Mr. Gray, of Cape Hosier, has observed that in the summer, after the 
water becomes warm, the scallops are apt to leave the sites frequented during the 
cooler months and seek deeper water or retire to grounds with a different character of 
bottom. The general opinion among fishermen in that section is that upon the return 
of cold weather, about October 1, they “ pod up” on hard, pebbly shoals, with a strong 
current, for the purpose, it is supposed, of undergoing the reproductive process. 
Information received in the fall of 1890 stated that no scallops were being found on 
some grounds that were profitably worked in the siiring of the same year, while new 
