[254] 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.
[255] δὐω, two; μόνος, single; γόνος, semen; πόρος, passage.
[256] Von Brunn, Arch. Mikr. Anat. xxiii. p. 413.
[257] Hist. Anim. v. 6 and 12, iv. 1, ed. Bekker, 1837.
[258] ‘On pourra constater si ce ne seraient pas des parties détachées de quelque céphalopode dans le but de servir à le fécondation,’ Hist. Nat. Helminthes, 1845, p. 482.
[259] Steenstrup, Ann. Mag. Nat. Hist. (2), xx. p. 81 f.
[260] C. Ashford, Journ. of Conch. iii. p. 239, iv. pp. 69, 108.
[261] W. E. Collinge, Zoologist, 1890, p. 276.
[262] Pelseneer, Comptes Rendus, cx. p. 1081.
[263] Kon. Vet. Akad. Handl. 1848, pp. 329–435.