624 
BULLETIN OF THE BUREAU OF FISHERIES 
spawns in the fall, is sexually mature in a year, and suitable for marketing the suc- 
ceeding winter, when a little over a year old, greatly simplifies the problem of regula- 
tion. It makes a winter market season ideal, for at that time the only scallops 
large enough to be profitably marketable are mature and have spawned. With 
spring spawning many, if not most, of the immature scallops would be large enough 
to market and might make up the bulk of the catch. The problem of conservational 
regulation with a winter market season would then be different and much more diffi- 
cult. Extreme destruction by man of mature scallops makes it difficult to determine 
the normal length of life. However, the knowledge that nearly all the scallops are 
immature in the summer makes it plain that scalloping at this time is wrong in prin- 
cipal and dangerous if carried on to an important extent or during a critical year. 
For scallop farming it is important to know that scallops ordinarily shift little, 
increase rapidly in bulk, and are ready to market when a little over a year old. It 
is also important to know that they die quickly out of the water and that transplant- 
ing, therefore, would be much more apt to kill them than it would oysters or clams. 
For a more detailed consideration of scallop conservation and of industrial 
scallop problems, generally, see Gutsell (1928). 
SUMMARY 
The bay scallop is of considerable economic importance. In value ($874,306 
per annum according to statistics quoted) it ranks third among the edible bivalves 
of the Nation, after the oyster and the hard clam Venus. It is an article of commerce 
intermittently from Massachusetts to North Carolina where these studies were made 
and where it is of great local importance. Recently a small commercial catch in 
Florida has been reported. 
Because of the types of interfilamentary connections to be found in certain 
European scallops, in the American bay scallop ( Pecten irradians), and in the sea 
scallop ( Pecten grandis ) with vascular connections, it is considered that if 
classification into large groups is to be based on gill structure the scallops belong 
at the end of the group of bivalve mollusks the gills of which typically are without 
vascular connections (Filibranchia) and adjacent to (and connecting with) the group 
typified by interfilamentary vascular connections (Eulamellibranchia). This agrees 
with the arrangement of Ridewood (1903) but not with his terminology. 
As stated by various writers, the range of the bay scallop is from Massachusetts 
to Florida or the Gulf of Mexico. It occurs principally in inclosed grassy waters of 
a depth varying from about a foot at ordinary low water to as much as 60 feet (Reld- 
ing). In North Carolina it occurs principally in water less than 6 feet deep and of a 
normal salinity range of 38 parts per mille to 20 parts per milie. 
Structure and function are considered at some length and in considerable detail. 
Studies were principally of living and fresh material. 
Evidence from the examination of gonads and from periodic collections for 
young points to a spawning season beginning in mid or late summer, attaining its 
height in the fall, and continuing into January. 
The form believed to be the late veliger or prodissoconch is equivalve, whereas 
Belding described and figured the late prodissoconch as inequivalve. 
Sexual maturity and a large size are attained typically in the fall at an age of 
1 year. In the vast majority of cases death comes at the hand of man before the 
next spring. So extreme is this destruction that the normal length of life has not 
been determined. A few individuals live to be about 2 years old and to spawn a 
