PROGRESS IN BIOLOGICAL INQUIRIES, 1939 71 
with the conditions existing in November 1938, the density of the star- 
fish population in different areas of the Sound in March 1939 remained 
virtually the same. In general, starfish were rather scarce or entirely 
absent. Even in the most heavily infested area between Charles Island 
and Stratford Point they did not exceed 77 per sample. The majority 
of the samples contained from 1 to 5 starfish only. The second survey, 
made in November, revealed a tremendous increase in the starfish popu- 
lation throughout the entire growing section. From 25 to 100 times 
as many were found in November as were found in March. The 
majority of starfish were of the 1939 set. The large increase in the 
numbers of starfish compelled the oystermen to carry on a vigorous 
campaign of eradication. A new method, consisting of spreading lime 
over the infested areas, was put into general use and proved to be 
quite satisfactory. At present this method is being relied upon by 
many oyster-growing companies operating in Connecticut, New York, 
and Rhode Island waters. 
Oyster drill—During the last few years the common oyster drill 
(Urosalpina cinerea) has become very numerous in the waters of Long 
Island Sound, where it destroys large numbers of oysters. Experi- 
ments conducted at Milford Laboratory by Mr. Engle showed that the 
period of feeding lasted from late May until late November in 1989, 
with the peak of activity between the middle of August and the middle 
of September. The voracity of drills was observed under laboratory 
conditions. Several young Urosalpinz, less than 30 days old and about 
2 mm. long, were put in an aquarium with oyster spat ranging from 
2to4mm. in diameter. Within 15 days 2 drills destroyed 142 oysters. 
The deposition of drill egg cases began early in June, when the water 
temperature was about 16.0° C. (60.8° F.), and continued through 
October. The heaviest ege case laying occurred from the middle of 
July through the middle of August. 
Boring clam.—Another problem which has been attacked by the 
staif of the Pensacola Laboratory is the boring clam, J/artesia, which is 
common on many parts of the Gulf coast. This clam apparently enters 
the shell wall at a small size and enlarges the cavity 1t occupies as it 
grows larger. Nothing is known of its life history at yet, save that 
it isa lamellibranch, and presumably has a free-swimming larval stage. 
In Mississippi Sound, near Biloxi and Gulfport, the infestation has be- 
gun to assume serious proportions. Fifteen years ago Dr. Galtsoff, af- 
ter a through survey, reported no boring clams in that region. Oyster- 
men claim that they have appeared only in the last few years, and now, 
on some grounds, living oysters are so infested with the clams that the 
shells crumble under slight pressure. It is not unusual for an oyster 
about 3 inches long to have 100 or more boring clams occupying each 
of its valves. As the clams grow to about one-fourth inch in diameter 
they consume the shell, leaving little protection for the oyster living 
within. An investigation of the life history of the boring clam, its 
habits and tolerance of environmental factors, has been undertaken at 
the Pensacola Station. 
Sporozoan parasite —A long-continued investigation of the sporo- 
zoan parasite of the oyster carried on by Dr. Prytherch at Beaufort, 
N. C., has been completed. A detailed description of the development 
and microscopic structure of this pest is incorporated in the manuscript 
entitled “The life cycle and morphology of Vematopsis ostrearum, sp. 
