Mollusc (non-marine) data for Great Britain and Ireland

Quality Control

Initial validation of the records was carried out by automatically checking that the grid reference occurred within the recorded Vice County stated. The distribution maps of the data were visually checked by Michael Kerney prior to publication of the atlas and this method has been continued to check species distributions. Records are checked by the National Recorder against the known distribution.

Method steps

1. The records in this dataset are the results of the Conchological Societies non-marine census which has been run since 1876. The dataset includes all digital records held by the Society up to the time of publication. The dataset is an amalgam of the cards that were originally digitised at 10km square as part of the publication of the non-marine mollusc atlas as well as a redigitisation of those records at finer scales and a substantial number of more recent records. All the survey data were collected by members of the Conchological Society. Recording is still continuing although no publications are expected at present.

The dataset covers both Britain and Ireland though the data available for Ireland is not definitive. Within Great Britain the sampling is biased towards England with a lower level of sampling in Scotland. Note that some effort was made ahead of the publication of the atlas to sample areas which had been under-recorded. The Conchological Society does include the Channel Islands, but these records are not included in the database.