AbstractA comparative study of the sexual sequence is carried out in four Oniscoidea of the ligiid seriesPorcellio laevis, Metoponorthus sexfasciatus(Porcellionidae),Armadillidium vulgare(Armadillidiidae) andArmadillo officinalis(Armadillidae). The differences between the four species chiefly appear in the precopulatory manoeuvres. The integration of coiling or uncoiling reactions in the sexual sequence of coiling forms is studied in two genera:ArmadillidiumandArmadillo. Results of the behavioral study provide information about the evolution of the group.