Page:Descent of Man 1875.djvu/667

Rh

* Hyelaphus porcinus, 546.
 * Hygrogonus, 345.
 * Hyla, singing species of, 350.
 * Hylobates, absence of the thumb in, 51; upright progression of some species of, 52; maternal affection in a, 70; direction of the hair on the arms of species of, 151; females of, less hairy below than males, 558.
 * agilis, 51; hair on the arms of, 151; musical voice of the, 527; superciliary ridge of, 558; voice of, 567.
 * hoolock, sexual difference of colour in, 537.
 * lar, 51; hair on the arms of, 151.
 * leuciscus, 51; song of, 568.
 * syndactylus, 51; laryngeal sac of, 527.
 * Hylophila prasinana, 308.
 * Hymenoptera, 291; large size of the cerebral ganglia in, 54; classification of, 148; sexual differences in the wings of, 277; aculeate, relative size of the sexes of, 279.
 * Hymenopteron, parasitic, with a sedentary male, 221.
 * Hyomoschus aquaticus, 547.
 * Hyperythra, proportion of the sexes in, 251.
 * Hypogymna dispar, sexual difference of colour in, 316.
 * Hypopyra, coloration of, 315.


 * Ibex, male, falling on his horns, 508; beard of the, 531.
 * Ibis, white, change of colour of naked skin in, during the breeding season, 389; scarlet, young of the, 481.
 * tantalus, age of mature plumage in, 483; breeding in immature plumage, 484.
 * Ibises, decomposed feathers in, 385; white, 492; and black, 493.
 * Ichneumonidæ, difference of the sexes in, 292.
 * Ichthyopterygia, 37.
 * Ichthyosaurians, 159.
 * Idiots,. microcephalous, their characters and habits, 35; hairiness and animal nature of their actions, 36; microcephalous, imitative faculties of, 87.
 * Iguana tuberculata, 354.
 * Iguanas, 354.
 * Illegitimate and legitimate children, proportion of the sexes in, 244.
 * Imagination, existence of, in animals, 74.
 * Imitation, 68; of man by monkeys, 72; tendency to, in monkeys, microcephalous idiots and savages, 87; influence of, 129.
 * Immature plumage of birds, 463, 466.
 * Implacentata, 157.
 * Implements, employed by monkeys, 81; fashioning of, peculiar to man, 82.
 * Impregnation, period of, influence of, upon sex, 245.
 * Improvement, progressive, man alone supposed to be capable of, 79.
 * Incisor teeth, knocked out or filed by some savages, 575.
 * Increase, rate of, 44; necessity of checks in, 47.
 * Indecency, hatred of, a modern virtue, 119.
 * India, difficulty of distinguishing the native races of, 167; Cyprinidæ of, 343; colour of the beard in races of men of, 558.
 * Indian, North American, honoured for scalping a man of another tribe, 117.
 * Individuality, in animals, 83.
 * Indopicus carlotta, colours of the sexes of, 458.
 * Infanticide, prevalence of, 46, 117, 256; supposed cause of, 577; prevalence and causes of, 591 et seq.
 * Inferiority, supposed physical, of man, 64.
 * Inflammation of the bowels, occurrence of, in Cebus Azaræ, 7.
 * Inheritance, 27; of long and short sight, 33; of effects of use of vocal and mental organs, 88; of moral tendencies, 123, 126; laws of, 227; sexual, 232; sexually limited, 444.
 * Inquisition, influence of the, 141.
 * Insanity, hereditary, 28.
 * Insect, fossil, from the Devonian, 289.
 * Insectivora, 534; absence of secondary sexual characters in, 218.