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During their investigations on parasitism of fishes and birds in the lagoon of Brusc (Var), the authors have discovered the life cycle of Cardiocephalus longicollis. Cercariae of pharyngeate furcocercous type develop in sporocysts in the digestive gland of the marine prosobranch Nassa corniculum. The cercaria is identified as Cercaria nassae (Dolgikh, 1965) from Nassa reticulata in Black sea; it closely resembles Cercaria nassa (Martin, 1945) from Ilyanassa obsolseta (syn. Nassa obsoleta) at Woods Hole (U.S.A.). Several intermediate hosts have been related; they are the marine fishes Diplodus annularis, D. vulgaris, Boops salpa, Pagellus mormyrus (Sparidae) and Belone belone (Scombresocidae). Metacercariae of tetracotyle type were found in the cavity of optical lobes of the brain. Experimental contamination of fishes: Potamoschistus microps, Blennius sp., Mugil cephalus and Syngnathus abaster has been negative; that of Diplodus annularis and D. sargus, positive. It allowed to follow the development from cercaria to tetracotyle. In Provence natural definitive hosts are Larus argentatus and L. ribidundus; contaminations of these birds with metacercariae experimentally raised in Diplodus annularis and D. vulgaris were successfull. Some observations are pointed out especially the development of the parasite in the definitive host, the organisation of tribocytic organ and the geographical distribution of the parasite.

The authors point out the ecological conditions required for the life-cycle development of Maritrema misenensis (A. Palombi, 1940). This Microphallid parasite occurs in waveless lagoons as well as along the waved marine coast. The first and second intermediate hosts found in these two habitats are not alike. Along the calm edges of the lagoon edges Cerithium mediterraneum (first host) and Orchestia mediterranea (second host) are found whereas along the rocky sea-coast C. rupestre (first host) and O. montagui (second host) are to be seen. The first intermediate hosts are heavily infected along the margin of the lagoon; the parasitism is decreasing gradually as we go away the edge. The infection of the second host depends on the behaviour both of Orchestia and cercariae. Numerous cercariae accumulate against along the very edge of the lagoon, exactly where Orchestia enter the sea-water. The Orchestia parasitism varies as you go along the coast and according to the seasons; it is also different whether you are dealing with males or females.

The life cycle of Maritrema misenensis (A. Palombi, 1940) n. comb. is described with illustrations. The sporocysts parasite the digestive gland of the Prosobranch snail Cerithium mediterraneum. The cercariae are the same as Cercaria misenensis, A. Palombi, 1940 described from Italian coast. The adults have been obtained by artificial infestations of Larus argentatus michaellis. Their morphological features are same as those of the caribbean species Maritrema patulus W.H. Coil, 1955. When the life cycle of the American species is pointed out, it will be possible to know whether there are two or only one species.

This paper deals with life-cycle of Renicola lari J. Timon-David, 1933. Description and illustration are given. Sporocyst development occurs inside the visceral mass of Cerithium mediterraneum and C. Rupestre (Mollusca Prosobranchia). Cercariae are planktonic; they are swallowed up by the second intermediate host, Atherina hepsetus and A. boyeri (Teleostean fishes). Cercariae perforate intestine wall. Metacercariae are encysted in liver. Adult flukes have been recovered in kidneys of uninfected Larus argentatus and L. ridibundus after exerimental contamination with naturally infected fishes. Cercariae of Renicola lari differ from Plagiorchid type cercariae by the following characters : stylet lacking ; very large excretory bladder ; they develop into metacercariae in fishes. Cercariae of R. lari seem to Rhodometope type cercariae ; they have the same excretory bladder. Cercariae of R. lari differ from Rhodometope cercariae in lacking fins on their tail.