External morphology and early development of Pleurobranchus (Oscanius) sp. from Gulf of Mannar

Abstract

In a dredge collection from the Gulf of Mannar at one and a half fathoms depth near the Central Marine Fisheries Research Institute at Mandapam Camp four numbers of a species of sea-slug under the genus Pleurobranchus Cuvier and subgenus Oscanius (Leach) (vide Thiele 1931) along with their egg ribbons were obtained on 25th December, 1960. To the best of our knowledge the form obtained has not so far been described, although Bergh (1905) in his Report on Opisthobranchiata of Siboga Expedition in Tafel II, Fig. 2, gives an almost identical form as Oscanius sp. Unfortu nately the original specimen of the Siboga Expedition as also the notes thereof were lost as stated under the legend to the figure referred to above.