Genitalia of the Group Geometridae of the Lepidoptera of the British Islands

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. As the penis forms an important, in many cases the most important, structure for purposes of differentiation, drawings of this organ have been added (on the right of each figure), but I would warn workers that it is...