manders, 102;
origin of, in embryo, 144;
of fish, 150, 152.

Giraffe, neck of, in relation to Lamarck's theory, 254.

Glacial periods, effects of, on distribution of plants and animals,
209, 210, and Appendix.

Goose, Frizzled, portrait of, 304.

Gorilla, _see_ Apes.

Gray, Professor Asa, 337

Great-toe, in man and apes, 79-81.

Grouse, 317-319

Growth, correlation of, 357, 362.

_Gymnotus_, 365, 367.

H.

Haeckel, on analogy between species and languages, 32;
on reproduction as discontinuous growth, 105, 106;
his ideal primitive vertebrate, 143, 144.

Hair, vestigial characters of, in man, 89-92.

Hales, 3.

Haller, 3.

Hamilton, Sir William, 272.

Hands, 51-55, 66, 80-82, 174-192.

Hare, 318, 319.

Hartmann, on flattening of early human tibiae, 96.

Harvey, on Lord Bacon's writings, 2.

Heart, development of, 154.

Heilprin, on skulls of deer, 198, 199;
on fossil shells, 201, 202.

Hen, ovum of, 122.

Heredity, in relation to classification, 28-31;
in relation to embryology, 98-102;
chromatin-fibres in relation to, 134;
in relation to theories of organic evolution, 253-255, 260-264, 377.

Hermit-crabs, 62-65, 288, 289.

_Heteromera_, 233.

Hilgendorf, on shells of _Planorbis_, 201.

_Hipparion_, 191, 192.

Hippopotamus, foot of, 187.

Hog, _see_ Pig.

Homology, 38, 50-65, 176, 177, 347-350, 357-359.

Homopterous insect, imitating leaf-cutting ants, 331, 332.

Hooker, Sir Joseph, on flora of St. Helena, 234.

Horns, 98-100, 167-169.

Horse, eye of, 75;
limb-bones of, 176, 177, 186, 188-192;
teeth of, 189-191;
portraits of domesticated breeds of, 309.

Human, _see_ Man.

_Humerus_, perforations of, in quadrumana and man, 94, 95.

Humming-birds, restricted to the New World, 211.

Hunter, 3;
on ear of whale, 65.

Huxley, Prof., on mechanical selection, 283;
on age of the earth, 435, 436;
on Dr. Whewell, 243.

Hyatt, on shells of _Planorbis_, 201.

_Hydra_, 111, 122.

_Hyrax_, foot of, 185, 186.

I.

Ignorance, argument from, 41, 42, 49.

Illative Sense, 6.

Imitative colours, 317-323, 326-332.

Infant, feet of, 78, 79;
grasping power of, 81.

Infertility, inter-specific, in relation to natural selection, 374-376.

Insects, wingless, 68-70;
in primary formations, 163, Appendix;
on oceanic islands, 224-238;
in relation to galls, 293-295, 446-448;
defensive colouring of, 321-332;
fertilizing flowe