offspring than other males. The offspring of the former, although
variously intercrossed, would either inherit the peculiarities of their
fathers or transmit an increased tendency to vary in the same manner.
Consequently the whole body of males inhabiting the same country would tend
from the effects of constant intercrossing to become modified almost
uniformly, but sometimes a little more in one character and sometimes in
another, though at an extremely slow rate; all ultimately being thus
rendered more attractive to the females. The process is like that which I
have called unconscious selection by man, and of which I have given several
instances. In one country the inhabitants value a fleet or light dog or
horse, and in another country a heavier and more powerful one; in neither
country is there any selection of individual animals with lighter or
stronger bodies and limbs; nevertheless after a considerable lapse of time
the individuals are found to have been modified in the desired manner
almost uniformly, though differently in each country. In two absolutely
distinct countries inhabited by the same species, the individuals of which
can never during long ages have intermigrated and intercrossed, and where,
moreover, the variations will probably not have been identically the same,
sexual selection might cause the males to differ. Nor does the belief
appear to me altogether fanciful that two sets of females, surrounded by a
very different environment, would be apt to acquire somewhat different
tastes with respect to form, sound, or colour. However this may be, I have
given in my 'Descent of Man' instances of closely-allied birds inhabiting
distinct countries, of which the young and the females cannot be
distinguished, whilst the adult males differ considerably, and this may be
attributed with much probability to the action of sexual selection.


INDEX.

Abbot, C., on the battles of seals.

Abductor of the fifth metatarsal, presence of, in man.

Abercrombie, Dr., on disease of the brain affecting speech.

Abipones, marriage customs of the.

Abortion, prevalence of the practice of.

Abou-Simbel, caves of.

Abramis brama.

Abstraction, power of, in animals.

Acalles, stridulation of.

Acanthodactylus capensis, sexual differences of colour in.

Accentor Modularis.

Acclimatisation, difference of, in different races of men.

Achetidae, stridulation of the;
rudimentary stridulating organs in female.

Acilius sulcatus, elytra of the female.

Acomus, development of spurs in the female of.

Acridiidae, stridulation of the;
rudimentary stridulating organs in female.

Acromio-basilar muscle, and quadrupedal gait.

Acting.

Actiniae, bright colours of.

Adams, Mr., migration of birds;
intelligence of nut-hatch;
on the Bombycilla carolinensis.

Admiral butterfly.

Adoption of the young of other animals by female monkeys.

Advancement in the organic scale, Von Baer's definition of.

Aeby, on the difference between the skulls of man and the quadrumana.

Aesthetic faculty, not highly developed in savages.

Affection, maternal;
manifestation of, by animals;
parental and filial, partly the result of natural selection;
mutual, of birds;
shewn by birds in confinement, for certain persons.

Africa, probably the birthplace of man;
South, crossed population of;
South, retention of colour by the Dutch in;
South, proportion of the sexes in the butterflies of;
tattooing practised in;
Northern, coiffure of natives of.

Agassiz, L., on conscience in dogs;
on the coincidence of the races of man with zoological provinces;
on the number of species of man;
on the courtship of the land-snails;
on the brightness of the colours of male fishes during the breeding season;
on the frontal protuberance of the males of Geophagus and Cichla;
male fishes hatching ova in their mouths;
sexual differences in colour of chromids;
on the slight sexual differences of the South Americans;
on the tattooing of the Amazonian Indians.

Age, in relation to the transmission of characters in birds;
variation in accordance with, in birds.

Agelaeus phoeniceus.

Ageronia feronia, noise produced by.

Agrion, dimorphism in.

Agrion Ramburii, sexes of.

Agrionidae, difference in the sexes of.

Agrotis exclamationis.

Ague, tertian, dog suffering from.

Ainos, hairiness of the.

Aitchison, Mr., on sheep.

Aithurus polytmus, young of.

Albino birds.

Alca torda, young of.

Alces palmata.

Alder and Hancock, MM., on the nudi-branch mollusca.

Allen, J.A., vigour of birds earliest hatched;
effect of difference of temperature, light, etc., on birds;
colours of birds;
on the relative size of the sexes of Callorhinus ursinus;
on the name of Otaria jubata;
on the pairing of seals;
on sexual differences in the colour of bats.

Allen, S., on the habits of Hoplopterus;
on the plumes of herons;
on the vernal moult of Herodius bubulcus.

Alligator, courtship of the male;
roaring of the male.

Amadavat, pugnacity of male.

Amadina Lathami, display of plumage by the male.

Amadina castanotis, display of plumage by the male.

Amazons, butterflies of the;
fishes of the.

America, variation in the skulls of aborigines of;
wide range of aborigines of;
lice of the natives of;
general beardlessness of the natives of.

America, North, butterflies of;
Indians of, women a cause of strife among the;
Indians of, their notions of female beauty.

America, South, character of the natives of;
population of parts of;
piles of stones in;
extinction of the fossil horse of;
desert-birds of;
slight sexual difference of the aborigines of;
prevalence of infanticide in.

American languages, often highly artificial.

Americans, wide geographical range of;
native, variability of;
and negroes, difference of;
aversion of, to hair on the face.

Ammophila, on the jaws of.

Ammotragus tragelaphus, hairy forelegs of.

Amphibia, affinity of, to the ganoid fishes;
vocal organs of the.

Amphibians, breeding whilst immature.

Amphioxus.

Amphipoda, males sexually mature while young.

Amunoph III., negro character of, features of.

Anal appendages of insects.

Analogous variation in the plumage of birds.

Anas.

Anas acuta, male plumage of.

Anas boschas, male plumage of.

Anas histrionica.

Anas punctata.

Anastomus oscitans, sexes and young of;
white nuptial plumage of.

Anatidae, voices of.

Anax junius, differences in the sexes of.

Andaman islanders, susceptible to change of climate.

Anderson, Dr., on the tail of Macacus brunneus;
the Bufo sikimmensis;
sounds of Echis carinata.

Andreana fulva.

Anglo-Saxons, estimation of the beard among the.

Animals, domesticated, more fertile than wild;
cruelty of savages to;
characters common to man and;
domestic, change of breeds of.

Annelida, colours of.

Anobium tessellatum, sounds produced by.

Anolis cristatellus, male, crest of;
pugnacity of the male;
throat-pouch of.

Anser canadensis.

Anset cygnoides; knob at the base of the beak of.

Anser hyperboreus, whiteness of.

Antelope, prong-horned, horns of.

Antelopes, generally polygamous;
horns of;
canine teeth of some male;
use of horns of;
dorsal crests in;
dewlaps of;
winter change of two species of;
peculiar markings of.

Antennae, furnished with cushions in the male of Penthe.

Anthidium manicatum, large male of.

Anthocharis cardamines;
sexual difference of colour in.

Anthocharis genutia.

Anthocharis sara.

Anthophora acervorum, large male of.

Anthophora retusa, difference of the sexes in.

Anthropidae.

Anthus, moulting of.

Antics of birds.

Antigua, Dr. Nicholson's observations on yellow fever in.

Antilocapra americana, horns of.

Antilope bezoartica, horned females of;
sexual difference in the colour of.

Antilope Dorcas and euchore.

Antilope euchore, horns of.

Antilope montana, rudimentary canines in the young male of.

Antilope niger, sing-sing, caama, and gorgon, sexual differences in the
colours of.

Antilope oreas, horns of.

Antilope saiga, polygamous habits of.

Antilope strepsiceros, horns of.

Antilope subgutturosa, absence of suborbital pits in.

Antipathy, shewn by birds in confinement, to certain persons.

Ants, large size of the cerebral ganglia in;
soldier, large jaws of;
playing together;
memory in;
intercommunication of, by means of the antennae;
habits of;
difference of the sexes in;
recognition of each other by, after separation.

Ants White, habits of.

Anura.

Apatania muliebris, male unknown.

Apathus, difference of the sexes in.

Apatura Iris.

Apes, difference of the young, from the adult;
semi-erect attitude of some;
mastoid processes of;
influences of the jaw-muscles on the physiognomy of;
female, destitute of large canines;
building platforms;
imitative faculties of;
anthropomorphous;
probable speedy extermination of the;
Gratiolet on the evolution of;
canine teeth of male;
females of some, less hairy beneath than the males.

Apes, long-armed, their mode of progression.

Aphasia, Dr. Bateman on.

Apis mellifica, large male of.

Apollo, Greek statues of.

Apoplexy in Cebus Azarae.

Appendages, anal, of insects.

Approbation, influence of the love of.

Aprosmictus scapulatus.

Apus, proportion of sexes.

Aquatic birds, frequency of white plumage in.

Aquila chrysaetos.

Arab women, elaborate and peculiar coiffure of.

Arabs, fertility of crosses with other races;
gashing of cheeks and temples among the.

Arachnida.

Arakhan, artificial widening of the forehead by the natives of.

Arboricola, young of.

Archeopteryx.

Arctiidae, coloration of the.

Ardea asha, rufescens, and coerulea, change of colour in.

Ardea coerulea, breeding in immature plumage.

Ardea gularis, change of plumage in.

Ardea herodias, love-gestures of the male.

Ardea ludoviciana, age of mature plumage in;
continued growth of crest and plumes in the male of.

Ardea nycticorax, cries of.

Ardeola, young of.

Ardetta, changes of plumage in.

Argenteuil.

Argus pheasant, display of plumage by the male;
ocellated spots of the;
gradation of characters in the.

Argyll, Duke of, on the physical weakness of man;
the fashioning of implements peculiar to man;
on the contest in man between right and wrong;
on the primitive civilisation of man;
on the plumage of the male Argus pheasant;
on Urosticte Benjamini;
on the nests of birds.

Argynnis, colouring of the lower surface of.

Aricoris epitus, sexual differences in the wings of.

Aristocracy, increased beauty of the.

Arms, proportions of, in soldiers and sailors;
direction of the hair on the.

Arms and hands, free use of, indirectly correlated with diminution of
canines.

Arrest of development.

Arrow-heads, stone, general resemblance of.

Arrows, use of.

Arteries, variations in the course of the.

Artery, effect of tying, upon the lateral channels.

Arthropoda.

Arts practised by savages.

Ascension, coloured incrustation on the rocks of.

Ascidia, affinity of the lancelet to;
tad-pole like larvae of.

Ascidians, bright colours of some.

Asinus, Asiatic and African species of.

Asinus taeniopus.

Ass, colour-variations of the.

Ateles, effects of brandy on an;
absence of the thumb in.

Ateles beelzebuth, ears of.

Ateles marginatus, colour of the ruff of;
hair on the head of.

Ateuchus cicatricosus, habits of.

Ateuchus stridulation of.

Athalia, proportions of the sexes in.

Atropus pulsatorius.

Attention, manifestations of, in animals.

Audouin, V., on a hymenopterous parasite with a sedentary male.

Audubon, J.J., on the pinioned goose;
on the speculum of Mergus cucullatus;
on the pugnacity of male birds;
on courtship of Caprimulgus;
on Tetrao cupido;
on Ardea nycticorax;
on Sturnella ludoviciana;
on the vocal organs of Tetra cupido;
on the drumming of the male Tetrao umbellus;
on sounds produced by the nightjar;
on Ardea herodias and Cathartes jota;
on Mimus polyglottus;
on display in male birds;
on the spring change of colour in some finches;
on migration of mocking thrushes;
recognition of a dog by a turkey;
selection of mate by female birds;
on the turkey;
on variation in the male scarlet tanager;
on the musk-rat;
on the habits of Pyranga aestiva;
on local differences in the nests of the same species of birds;
on the habits of woodpeckers;
on Bombycilla carolinensis;
on young females of Pyranga aestiva acquiring male characters;
on the immature plumage of thrushes;
on the immature plumage of birds;
on birds breeding in immature plumage;
on the growth of the crest and plume in the male Ardea ludoviciana;
on the change of colour in some species of Ardea.

Audobon and Bachman, MM., on squirrels fighting;
on the Canadian lynx.

Aughey, Prof., on rattlesnakes.

Austen, N.L., on Anolis cristatellus.

Australia, not the birthplace of man;
half-castes killed by the natives of;
lice of the natives of.

Australia, South, variation in the skulls of aborigines of.

Australians, colour of new-born children of;
relative height of the sexes of;
women a cause of war among the.

Axis deer, sexual difference in the colour of the.

Aymaras, measurements of the;
no grey hair among the;
hairlessness of the face in the;
long hair of the.

Azara, on the proportion of men and women among the Guaranys;
on Palamedea cornuta;
on the beards of the Guaranys;
on strife for women among the Guanas;
on infanticide;
on the eradication of the eyebrows and eyelashes by the Indians of
Paraguay;
on polyandry among the Guanas;
celibacy unknown among the savages of South America;
on the freedom of divorce among the Charruas.

Babbage C., on the greater proportion of illegitimate female births.

Babirusa, tusks of the.

Baboon, revenge in a;
rage excited in, by reading;
manifestation of memory by a;
employing a mat for shelter against the sun;
protected from punishment by its companions.

Baboon, Cape, mane of the male;
Hamadryas, mane of the male.

Baboon, effects of intoxicating liquors on;
ears of;
diversity of the mental faculties in;
hands of;
habits of;
variability of the tail in;
manifestation of maternal affection by;
using stones and sticks as weapons;
co-operation of;
silence of, on plundering expeditions;
apparent polygamy of;
polygamous and social habits of.

Baboons, courtship of.

Bachman, Dr., on the fertility of mulattoes.

Baer, K.E. von, on embryonic development;
definition of advancement in the organic scale.

Bagehot, W., on the social virtues among primitive men;
slavery formerly beneficial;
on the value of obedience;
on human progress;
on the persistence of savage tribes in classical times.

Bailly, E.M., on the mode of fighting of the Italian buffalo;
on the fighting of stags.

Bain, A., on the sense of duty;
aid springing from sympathy;
on the basis of sympathy;
on the love of approbation etc.;
on the idea of beauty.

Baird, W., on a difference in colour between the males and females of some
Entozoa.

Baker, Mr., observation on the proportion of the sexes in pheasant-chicks.

Baker, Sir S., on the fondness of the Arabs for discordant music;
on sexual difference in the colours of an antelope;
on the elephant and rhinoceros attacking white or grey horses;
on the disfigurements practised by the negroes;
on the gashing of the cheeks and temples practised in Arab countries;
on the coiffure of the North Africans;
on the perforation of the lower lip by the women of Latooka;
on the distinctive characters of the coiffure of central African tribes;
on the coiffure of Arab women.

"Balz" of the Black-cock.

Bantam, Sebright.

Banteng, horns of;
sexual differences in the colours of the.

Banyai, colour of the.

Barbarism, primitive, of civilised nations.

Barbs, filamentous, of the feathers, in certain birds.

Barr, Mr., on sexual preference in dogs.

Barrago, F., on the Simian resemblances of man.

Barrington, Daines, on the language of birds;
on the clucking of the hen;
on the object of the song of birds;
on the singing of female birds;
on birds acquiring the songs of other birds;
on the muscles of the larynx in song-birds;
on the want of the power of song by female birds.

Barrow, on the widow-bird.

Bartels, Dr., supernumerary mammae in men.

Bartlett, A.D., period of hatching of bird's eggs;
on the tragopan;
on the development of the spurs in Crossoptilon auritum;
on the fighting of the males of Plectopterus gambensis;
on the Knot;
on display in male birds;
on the display of plumage by the male Polyplectron;
on Crossoptilon auritum and Phasianus Wallichii;
on the habits of Lophophorus;
on the colour of the mouth in Buceros bicornis;
on the incubation of the cassowary;
on the Cape Buffalo;
on the use of the horns of antelopes;
on the fighting of male wart-hogs;
on Ammotragus tragelaphus;
on the colours of Cercopithecus cephus;
on the colours of the faces of monkeys;
on the naked surfaces of monkeys.

Bartlett, on courting of Argus pheasant.

Bartram, on the courtship of the male alligator.

Basque language, highly artificial.

Bate, C.S., on the superior activity of male crustacea;
on the proportions of the sexes in crabs;
on the chelae of crustacea;
on the relative size of the sexes in crustacea;
on the colours of crustacea.

Bateman, Dr., tendency to imitation in certain diseased states;
on Aphasia.

Bates, H.W., on variation in the form of the head of Amazonian Indians;
on the proportion of the sexes among Amazonian butterflies;
on sexual differences in the wings of butterflies;
on the field-cricket;
on Pyrodes pulcherrimus;
on the horns of Lamellicorn beetles;
on the colours of Epicaliae, etc.;
on the coloration of tropical butterflies;
on the variability of Papilio Sesostris and Childrenae;
on male and female butterflies inhabiting different stations;
on mimicry;
on the caterpillar of a Sphinx;
on the vocal organs of the umbrella-bird;
on the toucans;
on Brackyurus calvus.

Batokas, knocking out two upper incisors.

Batrachia, eagerness of male.

Bats, scent-glands;
sexual differences in the colour of;
fur of male frugivorous.

Battle, law of;
among beetles;
among birds;
among mammals;
in man.

Beak, sexual difference in the forms of the;
in the colour of the.

Beaks, of birds, bright colours of.

Beard, development of, in man;
analogy of the, in man and the quadrumana;
variation of the development of the, in different races of men;
estimation of, among bearded nations;
probable origin of the.

Beard, in monkeys;
of mammals.

Beautiful, taste for the, in birds;
in the quadrumana.

Beauty, sense of, in animals;
appreciation of, by birds;
influence of;
variability of the standard of.

Beauty, sense of, sufficiently permanent for action of sexual selection.

Beaven, Lieut., on the development of the horns in Cervus Eldi.

Beaver, instinct and intelligence of the;
voice of the;
castoreum of the.

Beavers, battles of male.

Bechstein, on female birds choosing the best singers among the males;
on rivalry in song-birds;
on the singing of female birds;
on birds acquiring the songs of other birds;
on pairing the canary and siskin;
on a sub-variety of the monk pigeon;
on spurred hens.

Beddoe, Dr., on causes of difference in stature.

Bee-eater.

Bees, pollen-baskets and stings of;
destruction of drones and queens by;
female, secondary sexual characters of;
proportion of sexes;
difference of the sexes in colour and sexual selection.

Beetle, luminous larva of a.

Beetles, size of the cerebral ganglia in;
dilatation of the foretarsi in male;
blind;
stridulation of.

Belgium, ancient inhabitants of.

Bell, Sir C., on emotional muscles in man;
"snarling muscles;"
on the hand.

Bell, T., on the numerical proportion of the sexes in moles;
on the newts;
on the croaking of the frog;
on the difference in the coloration of the sexes in Zootoca vivipara;
on moles fighting.

Bell-bird, sexual difference in the colour of the.

Bell-birds, colours of.

Belt, Mr., on the nakedness of tropical mankind;
on a spider-monkey and eagle;
habits of ants;
Lampridae distasteful to mammals;
mimicry of Leptalides;
colours of Nicaraguan frogs;
display of humming-birds;
on the toucans;
protective colouring of skunk.

Benevolence, manifested by birds.

Bennett, A.W., attachment of mated birds;
on the habits of Dromaeus irroratus.

Bennett, Dr., on birds of paradise.

Berbers, fertility of crosses with other races.

Bernicla antarctica, colours of.

Bernicle gander pairing with a Canada goose.

Bert, M., crustaceans distinguish colours.

Bettoni, E., on local differences in the nests of Italian birds.

Beyle, M., see Bombet.

Bhoteas, colour of the beard in.

Bhringa, disc-formed tail-feathers of.

Bianconi, Prof., on structures as explained through mechanical principles.

Bibio, sexual differences in the genus.

Bichat, on beauty.

Bickes, proportion of sexes in man.

Bile, coloured, in many animals.

Bimana.

Birds, imitations of the songs of other birds by;
dreaming;
killed by telegraph wires;
language of;
sense of beauty in;
pleasure of, in incubation;
male, incubation by;
and reptiles, alliance of;
sexual differences in the beak of some;
migratory, arrival of the male before the female;
apparent relation between polygamy and marked sexual differences in;
monogamous, becoming polygamous under domestication;
eagerness of male in pursuit of the female;
wild, numerical proportion of the sexes in;
secondary sexual characters of;
difference of size in the sexes of;
fights of male, witnessed by females;
display of male, to captivate the females;
close attention of, to the songs of others;
acquiring the song of their foster-parents;
brilliant, rarely good songsters;
love-antics and dances of;
coloration of;
moulting of;
unpaired;
male, singing out of season;
mutual affection of;
in confinement, distinguish persons;
hybrid, production of;
Albino;
European, number of species of;
variability of;
geographical distribution of colouring;
gradation of secondary sexual characters in;
obscurely coloured, building concealed nests;
young female, acquiring male characters;
breeding in immature plumage;
moulting of;
aquatic, frequency of white plumage in;
vocal courtship of;
naked skin of the head and neck in.

Birgus latro, habits of.

Birkbeck, Mr., on the finding of new mates by golden eagles.

Birthplace of man.

Births, numerical proportions of the sexes in, in animals and man;
male and female, numerical proportion of, in England.

Bischoff, Prof., on the agreement between the brains of man and of the
orang;
figure of the embryo of the dog;
on the convolutions of the brain in the human foetus;
on the difference between the skulls of man and the quadrumana;
resemblance between the ape's and man's.

Bishop, J., on the vocal organs of frogs;
on the vocal organs of cervine birds;
on the trachea of the Merganser.

Bison, American, co-operation of;
mane of the male.

Bitterns, dwarf, coloration of the sexes of.

Biziura lobata, musky odour of the male;
large size of male.

Blackbird, sexual differences in the;
proportion of the sexes in the;
acquisition of a song by;
colour of the beak in the sexes of the;
pairing with a thrush;
colours and nidification of the;
young of the;
sexual difference in coloration of the.

Black-buck, Indian, sexual difference in the colour of the.

Blackcap, arrival of the male, before the female;
young of the.

Black-cock, polygamous;
proportion of the sexes in the;
pugnacity and love-dance of the;
call of the;
moulting of the;
duration of the courtship of the;
and pheasant, hybrids of;
sexual difference in coloration of the;
crimson eye-cere of the.

Black-grouse, characters of young.

Blacklock, Dr., on music.

Blackwall, J., on the speaking of the magpie;
on the desertion of their young by swallows;
on the superior activity of male spiders;
on the proportion of the sexes in spiders;
on sexual variation of colour in spiders;
on male spiders.

Bladder-nose Seal, hood of the.

Blaine, on the affections of dogs.

Blair, Dr., on the relative liability of Europeans to yellow fever.

Blake, C.C., on the jaw from La Naulette.

Blakiston, Captain, on the American snipe;
on the dances of Tetrao phasianellus.

Blasius, Dr., on the species of European birds.

Bledius taurus, hornlike processes of male.

Bleeding, tendency to profuse.

Blenkiron, Mr., on sexual preference in horses.

Blennies, crest developed on the head of male, during the breeding season.