Note 254 — Chapter V · REPRODUCTION—DEPOSITION OF EGGS—DEVELOPMENT OF THE FERTILISED OVUM—DIFFERENCES OF SEX—DIOECIOUS AND HERMAPHRODITE MOLLUSCA—DEVELOPMENT OF FRESH-WATER BIVALVES
Reading edition
Hermaphroditism seems to occur in (a) whole families, e.g. Anatinidae and the Septibranchia; (b) genera, e.g. Cyclas, Pisidium; (c) single species, e.g. in the generally dioecious genera Ostrea, Pecten, Cardium.