any but the Rhode Island drills . No oviposition was recorded for any of the 

 groups at 9 a C even though the experiment was extended for 14 days. It may be 

 significant, however, that the Rhode Island drills not only deposited egg cases at 

 a lower tempeiatu re (12°C) than any other group but also that 61% of this group 

 deposited cases at 18 "C, whereas oviposition in the nearest two groups, Long 

 Island Sound and New Jersey : only reached about 20%. The fact that 21 ,2% of the 

 New Jersey drills oviposited at iSfC, a temperature considerably higher than that 

 of the southern groups, may further separate the New Jersey drill population from 

 the latter . Loosanoff and Davis explain further that the somewhat inconsistent 

 results in the oviposition rates of the Long Island Sound drills may be explained, 

 in part, by the possible preponderance of males in the samples, They also point 

 out an interesting inconsistency when relating their laboratory findings to field 

 observations where they (Loosanoff, 1953) have found recently deposited drill egg 

 cases in 30 feet of water at a temperature of only 10. 9° C, or approximately 1° 

 lower than the lowest temperature given in Table 14, and at which in the laboratory 

 experiments the Long Island Sound drills laid no eggs . 



Loosanoff and Davis conclude from the averages presented in Table 14 that 

 Rhode Island and Long Island Sound drills appear to differ from the southern 

 groups in the higher percentage of the northern drills that commence turning over, 

 feeding, and ovipositing at lower temperatures than do the southern drills. 



The writer has included additional field data relating to physiological races 

 of Urosalpinx in Table 13 for comparison with Stauber s (1950) data and that of 

 Loosanoff and Davis (1950-51) in Table 14. Table 13 discloses a number of apparent 

 inconsistencies which may best be explained on the basis of incomparable accuracy 

 of many of the observations and/or ecological differences within the specific habitats 

 in which the drills were observed or collected. It is significant that Loosanoff and 

 Davis obtained movement of drills in all areas at lower temperatures Aan those 

 reported in Table 13, and especially for Virginia and North Carolina. Since Stauber's 

 figure of 5°C for movement of drills in Delaware Bay is based on movement into 

 traps his figure would be higher than that obtained in the close laboratory observa 

 tions. 



Federighi (1931c) observed feeding and drilling at 15° C in Virginia and 

 North Carolina, while Engle (1953) reports that it occurs as low as 7.6°C in North 

 Carolina, and Andrews and McHugh (pers, com.) recorded it at an average tempera- 

 ture of 6 ,5°Q in Virginia Loosanoff and Davis' data indicate that feeding and drilling 

 may commence at 6"C, a figure considerably lower than that given in the field data 

 in Table 13 , Again where data were collected by means of drill traps a lag would be 

 expected between drills in situ on the bottom and those which move into traps to feed. 



85 



