fect teeth, 12.
---- descended from several wild stocks, 18.
----, domestic instincts of, 213.
----, inherited civilisation of, 215.
----, fertility of breeds together, 254.
----, ---- of crosses, 268.
----, proportions of, when young, 444.
Domestication, variation under, 7.
Downing, Mr., on fruit-trees in America, 85.
Downs, North and South, 286.
Dragon-flies, intestines of, 190.
Drift-timber, 360.
Driver-ant, 240.
Drones killed by other bees, 202.
Duck, domestic, wings of, reduced, 11.
----, logger-headed, 182.
{494}
Duckweed, 385.
Dugong, affinities of, 414.
Dung-beetles with deficient tarsi, 135.
Dyticus, 386.

E.

Earl, Mr. W., on the Malay Archipelago, 395.
Ears, drooping, in domestic animals, 11.
----, rudimentary, 454.
Earth, seeds in roots of trees, 361.
Eciton, 238.
Economy of organisation, 147.
Edentata, teeth and hair, 144.
----, fossil species of, 339.
Edwards, Milne, on physiological divisions of labour, 115.
----, on gradations of structure, 194.
----, on embryonical characters, 418.
Eggs, young birds escaping from, 87.
Electric organs, 192.
Elephant, rate of increase, 64.
---- of glacial period, 141.
Embryology, 438.
Existence, struggle for, 60.
----, conditions of, 206.
Extinction, as bearing on natural selection, 109.
---- of domestic varieties, 111,
----, 317.
Eye, structure of, 187.
----, correction for aberration, 202.
Eyes reduced in moles, 137.

F.

Fabre, M. on parasitic sphex, 218.
Falconer, Dr., on naturalisation of plants in India, 65.
---- on fossil crocodile, 313.
---- on elephants and mastodons, 334.
---- and Cautley on mammals of sub-Himalayan beds, 340.
Falkland Island, wolf of, 394.
Faults, 285.
Faunas, marine, 348.
Fear, instinctive, in birds, 212.
Feet of bird, young molluscs adhering to, 385.
Fertility of hybrids, 249.
---- from slight changes in conditions, 267.
---- of crossed varieties, 268.
Fir-trees destroyed by cattle, 72.
---- ----, pollen of, 203.
Fish, flying, 182.
----, teleostean, sudden appearance of, 305.
---- eating seeds, 362, 387.
----, fresh-water, distribution of, 384.
Fishes, ganoid, now confined to fresh water, 107.
----, electric organs of, 192.
----, ganoid, living in fresh water, 321.
---- of southern hemisphere, 376.
Flight, powers of, how acquired, 182.
Flowers, struc