Monœcious Oysters

Abstract

IN NATURE of June 8, Ikusaku Amemiya gives a list of five species of oysters recorded as being monœcious, and later, July 6, Paul Pelseneer adds two additional species, making a total of seven altogether. The only moncecious species in this list recorded from Australasian waters is Ostrea angasi (the correct name has now been determined as O. sinuata Lamarck). After a careful examination of large numbers of oysters from the South Island of New Zealand, and also of the oysters which have been introduced from there into the Derwent River in Tasmania, I have come to the conclusion that the New Zealand oyster is specifically distinct from O. angasi. Hutton's name, O. lutaria, will therefore stand, and this species is larviparous and hermaphrodite.