Ichneumonidae, difference of the sexes in.
Ichthyopterygia.
Ichthyosaurians.
Idiots, microcephalous, their characters and habits; hairiness and animal nature of their actions; microcephalous, imitative faculties of.
Iguana tuberculata.
Iguanas.
Illegitimate and legitimate children, proportion of the sexes in.
Imagination, existence of, in animals.
Imitation, of man by monkeys; tendency to, in monkeys, microcephalous idiots and savages; influence of.
Immature plumage of birds.