PROGRESS IN BIOLOGICAL INQUIRIES, 1936 39 
this species is much lower than that found by Smith in A. vulgaris 
and much higher than that found by Cépéde in A. rubens. In Long 
Island Sound the percentage of parasitized males varies according to 
the locality, being as high as about 22 percent in the region of Strat- 
ford Point and as low as approximately 1 percent around New Haven. 
The fact that no parasites were found in recently metamorphosed 
starfish taken from a region where parasitism is common, and the fact. 
that infected larvae develop more slowly than normal ones, may 
indicate that all parasitized larvae die before metamorphosis and that 
the parasite does not remain quiescent until maturity. If such is 
the case, the method of parasitism in the adult starfish is yet to be 
discovered. 
Experiments to determine the attraction of starfish to various foods 
and the factors that control their movements were undertaken by Dr. 
Loosanoff in the Milford Laboratory, using one of the large tide- 
refilling tanks containing about 10,000 gallons of water. In carrying 
out this work care was exercised to eliminate the effects of lght, 
rapid changes in temperature, currents, and other factors which may 
direct the behavior,of starfish. While the work has not been com- 
pleted, the results obtained thus far can be summarized as follows: 
Starfish display but little preference for certain foods and because of 
poorly developed sense organs are unable to detect the presence of 
food until they come in contact with it. A preference for small 
mollusks rather than adults was evident. 
Oyster drill studies —Field studies of the drill population on repre- 
sentative tidal flat areas on the Eastern Shore region in Virginia 
carried out by Dr. H. F. Prytherch and William Hagen indicate that 
there are over 35,000,000 of these pests on the public oyster beds from 
Chincoteague to Cape Charles. On the private beds in Chincoteague 
Bay, where a considerable number of drills are removed each year by 
dredging and cleaning operations, there still remains a population of 
over 4,630,000 drills on approximately 4,000 acres of leased bottom, 
as judged by the results of experimental trapping operations. From 
the results of experiments on the rate of feeding of drills conducted 
under natural conditions in Bradfords Bay, in which medium-size 
drills were placed on areas planted with oysters of three different 
ages, it 1s estimated that the drill population on the Eastern Shore may 
destroy during one summer season approximately 500,000,000 seed and 
adult oysters. Records of 20 of the largest planters in Chincoteague 
Bay and vicinity show losses of marketable oysters ranging from 42 to 
100 percent over a period of 3 to 20 months on beds where drills were 
abundant. On various public beds, located on the tidal flats, the de- 
struction of adult oysters by drills ranged from 25 to 56 percent during 
the summer months. 
A brief summary of methods of drill control was given in Progress 
in Biological Inquiries, 1935. A detailed outline of procedure for 
reducing the numbers of these pests on oyster bottoms along the At- 
lantic coast has since been given in a report entitled “Natural History 
and Methods of Controlling the Common Oyster Drills (Urosalpinz 
cinerea Say and Hupleura caudata Say),” which was prepared for 
publication during 1936. 
Sporozoan parasite of the oyster—Studies of the life cycle and 
method of distribution of a sporozoan parasite of the oyster, con- 

