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MIGRATION 90 



Horizontal 90 



Spawning Migration 98 



"Sudden Appearance" of Drills on Oyster Grounds 99 



EUPLEURA CAUDATA- 101 



CONTROL 103 



Introduction 103 



Capture of Drills and Egg Cases 105 



Hand picking 105 



Forks , 106 



Concrete pillars 106 



Oyster dredges 106 



Deck screens 107 



Drill dredges 108 



Drill box traps 109 



Drill trapping 109 



Hydraulic suction dredges 112 



Fate of drills passing through suction dredges. . . 114 



Destruction of Drills and Egg Cases 115 



Desiccation 1 15 



Heat 115 



Hot water 115 



Flame 116 



Electricity 116 



Ultrasonics 117 



Fresh, brackish, and brine water . . . 117 



Magnesium chloride 118 



Copper sulfate 118 



Mercuric chloride 119 



Formalin 120 



Rotenone and amox 120 



Search for new compounds 120 



Physical and chemical barriers 121 



Biotic 123 



Utilization of Local Conditions 124 



Low Salinity 124 



Mud and sand bottom devoid of hard objects 125 



Temporary abandonment of bottom 125 



Removal of bottom trash 126 



Ratio of drills to prey 126 



Sharply pointed objects 127 



Exposure on intertidal bottom 127 



BENEFICIAL ASPECTS OF THE DRILL 127 



GENERAL DISCUSSION 127 



SUMMARY AND CONCLUSIONS 129 



ACKNOWLEDGMENTS 132 



LIST OF LITERATURE . 134 



