THE EVOLUTION OF THE MANTLE COMPLEX IN NU DIBRANCHIATE MOLLUSKS (GASTROPODA, NUDIBRANCHIA)

The evolution of the mantle complex of organs in nudibranchiate mollus cs and the development of respiratory apparatus are considered. The fo rmation of the organization of Nudibranchia, probably, took place unde r the direct influence of the detorsional process, which consisted of three stages. According to the extent of detorsion, four orders are co nsidered: Doridoxia ordo n. = Pseudoeuctenidiacea Wagele, 1989, which is characterized by the right-handed position of the mantle complex, P hyllida Ferussac, 1822 characterized by the terminal and ventral posit ion of the anus and adaptive gills, Corambida Minichev et Starobogatov , 1979 characterized by the ventral position of the ctenidium, Doridid a Odhner, 1934 characterized by the dorsal position of mantle complex. The detorsional process reaches its maximum in Doridida. In Doridina and Bathydoridina, the respiratory apparatus arises due to the polymer ization of primary gills, which are homologous to the ctenidium of anc estral forms having the shell.