[Biology of Cucullanus cirratus Müller, 1777 (Nematoda, Cucullanata)].

For the first time the description of the IInd and IIIrd stage larvae of C. cirratus from the submucous membrane of cod fish is given and the possibilities of the direct life cycle of C. cirratus are discussed. The scheme of the life cycle of C. cirratus is as follows. Eggs come out into water with faeces of the host at the stage of 2-4 blastomeres. 10-14 days after this the Ist stage larva hatches. After 4-5 days the Ist stage larva converts into the IInd stage by undergoing the first moulting. With food the IInd stage larva enters the stomach of cod fish. There it penetrates the submucous membrane of the stomach and converts into the IIIrd stage larva. After that the IIIrd stage larva migrates into the intestine where it undergoes the IIIrd and IVth moultings and reaches the adult stage.