Mating was observed in all tanks where the water level was allowed to fall (Treatment
A; Table 1). Mating lasted several hours and there was little movement of the animals
during mating. After about 10 days when the water level fell below 2 cm, the snails began
burrowing into the substratum. All females that were known to have mated produced eggs,
and there was no repeat mating. The mean number of eggs per female was 55 F 14 S.D.
(range 34– 84). Regression analysis revealed that there was no significant relationship
between female size and clutch size, although the larger females generally had a largerclutch size. In tanks where water level was maintained (Treatment B), no mating was
observed, and therefore, no eggs were produced.