A genus of leeches (class Hirudinea, family Gnathobdellidae). Species previously used in medicine are: Hirudo australis, Australian leech; Hirudo decora, American leech; Hirudo interrupta or Hirudo troctina, a North African leech; Hirudo medicinalis, speckled, Swedish, or German leech, the species previously in most general use; Hirudo m. officinalis, a variety of the preceding; Hirudo provincialis, the green or Hungarian leech; Hirudo quinquestriata, five-striped leech. [L. leech]