NATURAL HISTORY OF THE BAY SCALLOP 
623 
In the spring of 1928 I found a scallop of the market class of the preceding winter 
with a parasite present in the interlamellar septa of the gills and abundant in the 
wall of the stomach. Thereafter, every scallop of this class examined was found 
with this parasite in the walls of the stomach, generally in abundance. In the winter 
of 1928-29 it was again found prevalent. The appearance suggested a recently 
encysted miracidium, or a very young sporocyst. Later examination of Tennent’s 
(1906) account and illustrations (see his fig. 12) of Bucephalus haimeanus, and reex- 
amination of material, led me, as Tennent had been led, to doubt this. The partic- 
ular stage in the life of the parasite, which is assumed to be a Gasterostome, therefore, 
is not clear. Neither is its effect upon the scallop. With the oj^ster and some other 
lamellibranchs, Gasterostome infections render the host sterile, but there was no 
indication that the scallop was so affected by this parasite. In addition Tennent 
found evidence indicating that heavy infection rendered the oyster unable to resist 
unfavorable conditions. It is possible that the puzzling mortality which followed the 
apparently moderate freshening of the water over certain areas in the fall of 1928 
was due in part to lowered resistance from these parasites. 
Parasitic infection is worthy of consideration in connection with certain aspects 
of the life history of the scallop. The length of life of the scallop is unusually short. 
Moreover (as previously noted) Belding, working in Massachusetts, found that, 
although scallops generally died in the spring before they were 2 years old, gonadal 
development began as for a second spawning and continued to this end if the indi- 
vidual survived to the spawning season. This would suggest that some specific 
disease caused the mortality, and not old age. The intensity and the apparent 
universality of the. parasitic infection just described seemed a reasonable explanation. 
However, examination of scallops from Massachusetts stated to be 22 months old did 
not reveal the parasite. The decided natural mortality reported by Belding has not 
been observed by me (although it might be evident were it not for the extreme destruc- 
tion wrought by man) either in the time of year or at the age when he found it. 
As a higher vertebrate which feeds on the adult scallop in areas where parasitism 
is prevalent, the herring gull is suggested as a probable host of later stages of parasites 
of the scallop. 
Besides these definitely parasitic forms, a supposedly commensal crab, Pin- 
notheres maculatus Say, is to be found frequently in scallops in North Carolina. 
Although Hay and Shore (1918) state that only the female is common, three of four 
specimens sent to the National Museum and identified by Dr. Mary J. Rathbun 
proved to be males. As to the actual relationship between mollusk and crab the 
writer has no evidence to offer. 
IMPORTANCE OF A KNOWLEDGE OF SCALLOP BIOLOGY FOR 
CONSERVATION 
Scallop conservation at present is almost entirely 8 a matter of legal regulation. 
In order that regulation may be intelligently applied or the possibilities understood 
of supplementing it by more active means, such as scallop farming, a considerable 
knowledge of scallop biology is essential. Points of special importance for con- 
servational regulation are: Time of spawning, age at sexual maturity, age at market- 
ing, and length of life. Thus the knowledge that in North Carolina the bay scallop 
8 Planting small scallops on private beds seems to have been practiced on a small scale at Wareham, Mass., for some time and 
may become an important industry on Cape Cod. At Wareham the town also pays for the transplanting of seed soallops from 
flats to deep water to prevent winter killing. At Nantucket transplanting has been tried experimentally. 
