The family Cyclopidae Dana, 1853 belonging to the order Cyclopoida, currently contains nearly 50 genera and about 660 species. There is no existing modem systematic study of the entire family Cyclopidae nor of its constituent subfamilies Eucyclopinae or Cyclopinae. Most of the genera in the Cyclopidae are in urgent need of revision. Detailed descriptions of species are absolutely essential for a more rigorous definition of the generic diagnoses within the subfamilies Eucyclopinae and Cyclopinae. This volume gives diagnoses and identification keys for two genera within the subfamily Eucyclopinae, the genus Paracyclops and the genus Ochridacyclops.