Identification and distribution of bats of the genus Plecotus in England

The chief aim of this work was to find characters which would enable positive identifications to be made of living Plecotus auritus , Linn., 1758, and Plecotus austriacus Fischer, 1829. Previous work has related to museum material and usually did not give measurements which could be obtained from living bats. Sixteen indices per bat were at first measured, but only 12 of these were found to be significant and necessary for identification. The results were reasonably reproducible which allows their comparison with European data. Other diagnostic characters are described together with the known distribution in the British Isles. A summary of the known distribution and ecological data from Europe is given.