On the inheritance of sinistrality in Limnæa peregra

Abstract

In 1920, one of the authors commenced breeding experiments with sinistral examples of the normally dextral species Limnœa peregra . The animals were kindly given him from an aquarium by Mr. J. W. Taylor, and their sinistral parents had originally come from the pond near Leeds, in which for many years sinistral individuals of this species have been known to occur along with the normal form (8). The animals are sinistral, not only in shell twist but also in the arrangement of the soft parts. The abnormality is very rare, though the species is one of the most abundant fresh-water mollusca. Four individuals were taken young and put together in two pairs. Large glass jars were used, and in each was placed a piece of water-weed ( Elodea ) from sources known to be free from any possible connection with Limncœa peregra . Both pairs produced extensive broods which have now been carried down to the third, and in some few cases the fourth, filial generation.