possibility has been suggested before and no data are available to evaluate their 

 significance. 



It is evident that the inter- and mtraspecies food preferences of U.cinerea 

 of all ages should be reinvestigated on the basis of the growth rate, age, and 

 geographic location of isolated individuals as well as of aggregates of naturally 

 associated prey species. The response of very young drills to the ectocrines 

 of newly set bivalves especially merits investigations. 



Interrelations of Environmental Factors 



An analysis of individual environmental factors which collectively regulate 

 the behavior of the drill has merit as an aid to study and to interpretation . However, 

 Galtsoff et al (1937) and Stauber (1943), among others, are quick to point out that 

 the behavior of the drill is determined by the combined and antagonistic effects of 

 the environmental factors and cannot be attributed to a single cause . This emphasis 

 has special relevance to this synthesis . 



Biological Races 



The existence of "physiological species" in drill populations of widely 

 separated geographical areas has been indicated by Stauber (1950). He refers to 

 groups of drills which morphologically belong to the taxonomic species Uro salpinx 

 cmerea but which functiorally differ in their response to such ecological factors 

 as temperature. Until populations of "physiological species" are shown in fact to 

 be reproductively isolated from each other, it may be better to refer to them as 

 "physiological races" . Stauber has drawn his evidence from the existence of these 

 races from an analysis of data from Hampton Roads, Virginia (Federighi, 1931c), 

 Delaware Bay, New Jersey (Stauber, 1943), and Narragansett Bay, Rhode Island 

 (Gibbs, in Stauber, 1950), on temperatures which initiate locomotory movement, 

 drilling, and oviposition in the oyster drill in these three regions within its range 

 along the eastern coast of North America . The field data which Stauber presents 

 (Table 13), though not of comparable scope or detail, does appear to support his 

 hypothesis that physiological races exist in Urosalpinx. 



Stauber (1950) strongly emphasizes the need for carefully controlled lab- 

 oratory studies of physiological races, Loosanoff and Davis (1950-51) in a 

 laboratory study, designed to determine the variation in the initiation of activities 

 of oyster drills from 6 different geographic regions within a series of tempera- 

 tures spaced at 3°C intervals, have made an excellent beginnmg m their attempts 

 to determine whether these geographically isolated populations belong to different 

 physiological races . They emphasize the fact that their unpublished report is a 



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