• 1
    Revised descriptions of the British leeches of the family Erpobdellidae are given, together with accounts of their principal variations.
  • 2
    Since the British Erpobdellidae cannot with certainty be identified by examination of external characters, a technique is described for separating the genera and species by the shape of the genital atrium.
  • 3
    The leech Dina lineata (O. F. Müller, 1774) is recorded in Britain for the first time. It was collected in a roadside pond rich in calcium and in organic matter. It is an isolated occurrence, probably an example of recent colonization.
  • 4
    Erpobdella testacea cannot establish itself in an environment favourable to E. octoculata, but in conditions of sewage pollution, or low total alkalinity, E. testacea becomes dominant.
  • 5
    The division of E. octoculata into var. vulgaris and var. atomaria is of no taxonomic significance, and should be discontinued.
  • 6
    Trocheta subviridis has been found most frequently in London and the Home Counties, but also occurs in Manchester, Gloucester, Glamorgan and Oxford. It is frequently associated with sewage works.