(1987)
Volume
32
Part
6
Page from
365
In 14 of 16 studied species of Vertigo, Truncatellina and Columella among adult and subadult individuals aphallic ones occur. The aphally does not appear to result from the penis atrophy following copulation. Combined with small size, short life span, great seasonal fluctuations of population density, eggs laid singly, ability to self-fertilise and copulation of euphallic individuals with aphallic ones, it appears to be of a high selective value.