Summary.The male organ of British and continentalNelima silvatica(Simon) and ofN. doriae(Canestrini) is compared. That of the British examples is found to be identical with the continental species, but differs considerably from that ofN. doriae. External characters of BritishN. silvaticaare compared with those ofN. doriaeand with the British species ofLeiobunum. The habitats and range ofN. silvaticain the British Isles are discussed. It is shown to be the dominant species on Skokholm Island.