He released an unknown number of drills marked with pigment around a 

 stake on oyster ground m deep water in Hampton Roads. Virginia, Concentric 

 circles were marked at 25 foot intervals from the stake and 4 to 6 stations on 

 each of these circles were sampled for marked drills with tongs at weekly inter- 

 vals. In a period of 2-4 weeks the following marked drills were recovered: at 

 the stake, 2; at 25 feet, 9; 50 feet, 8; 75 feet, 2; 100 feet, 6; and 150 200 feet, 1. 

 These figures indicate that the majority of the drills moved at a possible maximum 

 rate of 7 feet per day or less; the fastest drill, 10 feet per day, The recovery of 

 only 28, or 5%, of the marked drills is explained by Fedenghi as due to the in- 

 efficient method of sampling and the possible loss of the identifying pigment. 



Federighi considered the Hampton Roads studies inconclusive so performed 

 further experiments in Beaufort, North Carolina, on oyster beds exposed or 

 slightly under water at low tide . Drills tagged with a numbered celluloid tag 

 fastened to the outer lip of the shell with a fine silver wire were planted around a 

 stake and the movements of each drill were followed daily at low water . In every 

 case, even after one month, he found that the tagged drills had not moved over 10 

 to 15 feet from the stake, an approximate rate of .4 to 0.5 foot per day. He 

 believes that this low rate was not due to the presence of ample food, because in 

 one experiment drills placed on firm bottom about 20 feet from an oyster bed in no 

 case moved to it . 



Federighi's data do not show that the results obtained in Beaufort corrobor- 

 ate those m Hampton Roads as he suggests, since in Beaufort drills moved no more 

 than 15 feet per month and in Hampton Roads a number migrated a possible 100 

 feet in the same time . His data suggest that the Beaufort drills, as indicated by 

 their low rate of movement, were impeded by the celluloid tag. 



Federighi concludes that the drill does not migrate extensively and that 

 its distribution has been accomplished principally by man in the culture of oysters, 



Sizer (1936) in field experiments in Delaware Bay deposited 711 marked 

 drills in the center of a 20 foot squaressurrounded by 28 drill traps on moderately 

 soft bottom in water about 15 feet deep, In four days when traps were tended he 

 found that 23% of the drills had travelled a distance of approximately 10 feet to the 

 bait, or about 2,5 feet per day. He repeated the experiment on hard bottom with 

 similar results but obtained a lower recovery of drills . Unfortunately traps were 

 not tended frequently enough to show the time of arrival of the marked drills at 

 the bait, and thus the actual rate of travel. Sizer states that the tides had no 

 apparent effect upon the direction of migration . 



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