Page 



Ova 29 



Egg Capsule 30 



ECOLOGICAL LIFE HISTORY 33 



Duration and Intensity of Oviposition 33 



Behavior of the Drill during Oviposition 35 



Egg Case Stages 36 



Incubation Period and Hatching Behavior 37 



Growth 40 



Growth rate, temperature, and latitude 44 



Growth rate and quality of food 45 



Sexual Maturity 47 



Longevity and Mortality 47 



- Food and Food Procurement 48 



Food preferences 48 



Drilling behavior 51 



Feeding behavior 54 



Effect of drilling on oysters 54 



Rate of destruction of prey 54 



RELATION TO ENVIRONMENTAL FACTORS 60 



Substratum 60 



Salinity 61 



Minimum survival salinity 61 



Movement 67 



Drilling and feeding 68 



Growth 68 



Oviposition 69 



Egg case stages 69 



pH 70 



Temperature 70 



Movement and hibernation 70 



Drilling and feeding 73 



Oviposition 74 



Tolerance to extremes of temperature 75 



Water Currents 75 



Gravity 76 



Light 77 



Ectocrines 77 



Interrelations of Environmental Factors 81 



Biological Races 81 



RELATION TO OTHER ANIMALS , 88 



• Cannibalism 88 



Other Species of Drilling Gastropods 89 



Sea Stars 89 



Fish 90 



Parasites 90 



