The study of the bulla from 18 lemaeopodid copepod species collected on 15 marine fish species and one freshwater fish species taken mainly from the Gulf of Lions in the Mediterranean Sea reveals a great morphological and structural variability. It is however possible to bring forth three general remarks: - the bulla of Lernaeopodidae parasites of Selachii have a remarkably constant structure probably due to the tegument nature of the attachment substratum; - the bulla of Lernaeopodidae parasites of Teleostei has a morphology influenced by the nature of the attachment tissue; - when species of a same genus (i.e. Clavellotis) are attached on a same organ, the shape of the bulla can constitute a taxonomic characteristic.