The copepodid phase of development of Euryte longicauda Philippi, 1843, is described from six stages associated with the bryozoan Flustra foliacea Linnaeus, 1758 Distinctive character states of the species include: distal teeth of mandibular gnathobase perpendicular to proximal teeth; distal seta of maxillular praecoxa with multiple cusps is perpendicular to proximal setae with one cusp; coxa of maxillule as a gnathobase perpendicular to praecoxa; maxillular palp comprised of two setae; fluted setae medially on the distal segment complex of both rami of swimming legs 1–4. The segmental homologies of the maxilla of E. longicauda are an unarmed syncoxa, a basis with two setiferous lobes, and a ramus of three segments. A re-examination of type specimens of E. bellatula Humes, 1991, and E. verecunda Humes, 1992, revealed a 2-segmented protopod for leg 5, confirming their inclusion in Euryte. Euryte longicauda retains the ancestral state for development of swimming legs 1–4. Development of the maxilliped suggests that E. longicaudata shares with Troglocyclops janstocki Rocha and Iliffe, 1994, and Neocyclops vicinus (Herbst, 1955) more states expressed during endopodal development of primitive cyclopoids, while endopodal development of the maxilliped of the remaining Cyclopidae is truncated. Euryte longicaudata, T. janstocki, and N. vicinus appear to belong to a monophyletic lineage at the base of the Cyclopidae; T. janstocki is most closely related to E. longicaudata.