hibernacula. In general movement within the sediment did not extend over a dis- 

 tance of 1/8 or 1/2 inch. In spite of occasional intervening warm periods buried 

 snails remained stationary for periods varying from a few days to 56 days . In 

 aquarium observations of a preliminary nature of drills from Bogue Sound, North 

 Carolina, the writer observed that at temperatures approximately above 15°C 

 some drills burrowed mole -like over the slate bottom of the aquarium in fine 

 shallow sand. This suggests that these southern drills respond to dropping tempera- 

 tures by burying at higher temperatures than the New Jersey drills . 



The writer's observations corroborate those of Galtsoff et al. (1937) on 

 the initiation and cessation of movement of New Jersey drills at low temperatures, 

 Stauber 's (1943) observation that drills for the most part do not creep off the 

 bottom onto elevated objects at temperatures below 5°C, and the observations of 

 these investigators that the drills which bury in the bottom move no deeper than the 

 siphon. Experiments with more carefully controlled stable and fluctuating tempera- 

 tures and utilizing drills from various latitudinal regions should reveal additional 

 information on the behavior of the oyster drill at low temperatures . 



Drilling and feeding 



Drilling and feeding in U . cmerea cease as the temperature of the water 

 drops to reported limits which vary not only for a given region but also for different 

 geographic locations (Tables 13 and 14). 



In Edge Cove, New Jersey, T. C. Nelson (1922) noted that drills fed during 

 the interval from April 13 to May 16 when water temperatures were rising from 

 15.6 to 18.3° C. In laboratory observations in Hampton Roads, Virginia, Feder- 

 lghi (1931c) found that drills begin to feed when the temperature of the water climbs 

 above approximately 15°C and ceases when it falls below this point. He also 

 noticed that drilling is completely halted by a sudden drop in temperature . In two 

 cases drills actively feeding in water at 27° C abruptly halted drilling and moved 

 away as the temperature fell suddenly to about 20 °C Federighi's observation led 

 Stauber (1943) to a possible explanation of partly drilled oysters found in cages in 

 Delaware Bay. Galtsoff et al, (1937) state that in Delaware Bay drilling occurs at 

 all temperatures between 9.5 and 28° C. Stauber (1943) confirmed Galtsoff et al., 

 but set the lower limit at 10° C. In addition he hypothesizes that since substances 

 emitted by the oyster stimulate the drill to seek the oyster as food, the lower limit 

 at which drilling begins and ceases in Delaware Bay may not be due to a critical 

 temperature value in the response of Uro salpinx. At temperatures between 5 and 

 10° C oysters are entering or emerging from hibernation with consequent considerable 

 variation in capacity to attract drills . This might account for the sizeable differences 

 in catches in the traps during this temperature xange, 



73 



