Environment, direct action of the, in causing differences between the sexes.
Envy, persistence of.
Eocene period, possible divergence of men during the.
Eolidae, colours of, produced by the biliary glands.
Epeira nigra, small size of the male of.
Ephemerae.
Ephemeridae.
Ephippiger vitium, stridulating organs of.
Epicalia, sexual differences of colouring in the species of.
Equus hemionus, winter change of.