Duck, harlequin, age of mature plumage in the; breeding in immature plumage.
Duck, long-tailed, preference of male, for certain females.
Duck, pintail, pairing with a widgeon.
Duck, voice of the; pairing with a shield-drake; immature plumage of the.
Duck, wild, sexual differences in the; speculum and male characters of; pairing with a pin-tail drake.
Ducks, wild, becoming polygamous under partial domestication; dogs and cats recognised by.
Dufosse, Dr., sounds produced by fish.
Dugong, nakedness of; tusks of.
Dujardin, on the relative size of the cerebral ganglia, in insects.
Duncan, Dr., on the fertility of early marriages; comparative health of married and single.