[Study of the larval stages of Monogenea of fishes (author's transl)].

The ciliate cells and the oncomiracidial chetotaxy of the following species are described: Among the Polyopisthocotylea : Gastrocotyle trachurii Van Bneden and Hesse, 1863, Gastrocotylidae, parasite of Trachurus trachurus (L.); Cyclocotyla bellones (Otto, 1821), Diclidophoradae, living on the Cymothoides Isopods of Sparidae : Boops boops (L.) and Spicara maena (L.) ; Mazocraes sp., Mazocraeidae, parasite of Sardinella maderensis (Lowe, 1841). Among the Monopisthocotylea : Ligophorus vanbenedeni (Parona and Perugia, 1890) and Onchocleidus principalis (Mizelle, 1936), Ancyrocephalidae, from Liza aurata (Risso, 1810) and Micropterus salmoïdes (Lacepède, 1802) respectively ; Furnistinia echeneis (Wagener, 1857), Diplectanidae, from Sparus aurata L. ; Calceostomella inerme (Parona and Perugia, 1889) Calceostomatidae, from Umbrina cirrhosa (L.) ; Calicotyl kröyeri Diesing, 1850, Monocotylidae, cloacal parasite of Raja clavata L. Results confirm the unity of the Polyopisthocotylea concerned. Among the Monopisthocotylea, a similar unity is recorded for the Dactylogyroïdea to which the Calceostomatidae have to be related. The oncomiracidial chetotaxy of Calicotyl kröyeri (Monocotylidae) is very close to that of the Dactylogyroïdea larvae and highly differs from that of the Capsalidae.