Stephenson (1930) recognized 15 genera, and Hrabě (1936 to 1963) has distinguished 17 genera of Lumbriculidae, a family of freshwater Oligochaeta. On the basis of the form and arrangements of the parts of the genital system, a scheme is suggested in which 12 genera of Lumbriculidae are recognized. These genera are defined and a key erected for their identification. Reasons for removing Dorydrilus Piguet, 1913 from the Lumbriculidae are presented and the family Dorydrilidae fam. n. is defined to accommodate the genus.