ANATOMY OF PSEUDOTRITONIA THIELE, 1912 AND NOTAEOLIDIA ELIOT, 1905 (GASTROPODA, OPISTHOBRANCHIA, NUDIBRANCHIA) FROM SIGNY ISLAND, ANTARCTICA

Several species of nudibranch molluscs are abundant amongst the rich b enthic hard substratum communities found close to the British Antarcti c Survey base at Signy Island, in the Atlantic sector of the Antarctic . Over the austral summer 1992/1993, two of the authors (LWB and DKAB) were able to collect some of the lesser known species of Nudibranchia at depths between 3 and 40 metres, using SCUBA. New information on mo rphology and anatomy of two of these species, Pseudotritonia gracilide ns Odhner, 1944 (Charcotiidae, Arminoidea) and Notaeolidia gigas Eliot , 1905 (Notaeolidiidae, Aeolidoidea) are presented in this paper. The validity of the species Notaeolidia gigas is strengthened.