Generalities—Darwin v. Wallace—The Peacock in his Pride—The “Display” of the Peacock Pheasant—The Splendour of the Argus Pheasant and the Marvel of its Eyes—The Frill of the Amherst Pheasant—Birds of Paradise in the Toils of Love—Inflated Suitors-Ruffs and Reeves—Fearsome Weapons and their Uses—Birds which dance-Musical Birds—The Bird’s Voice-box—The “Lek” of the Capercaillie—Instruments of Percussion—The Curious Performance of the Woodpecker 92 CHAPTER VII THE SEXUAL SELECTION THEORY AS APPLIED TO BIRDS Where the Rôle of the Sexes is reversed—Polygamy and how it is brought about—Coloration and Courtship—Instinctive Actions—The Importance of Landed Possessions—The Meaning of “Display”—The Springs of “Behaviour”—A New Light on the Wild-duck—The “Display” of the Great-crested Grebe—Some Neglected Factors 134 CHAPTER VIII SOME “COLD-BLOODED” LOVERS The Courtship of the Crocodile—Amorous Lizards—Horned Chameleons—A Flagellating Terrapin—The Frog that would a-wooing go—Some Musical Frogs—Some marvellous instincts in Newts 161 CHAPTER IX LOVE-MAKING AMONG THE FISHES Germinal variations—Fishes and Mate-hunting—Some Remarkable Sexual Differences displayed by the Teeth of “Rays”—The Double-eyed Fish—The Coloration of the Dragonet—Some Curious Facts about Salmon—The Strange Use of the Kidney in the Stickle-back—The Stickle-back and Parental Duties—Siamese Fighting-fish 175 CHAPTER X SOME OF THE “LOWER ORDERS” Butterflies and Moths, and the Coloration of their Wings—Female Choice and “Fine Feathers”—When Male Butterflies are Dominant—Sexual Selection among Butterflies—Abortive Experiments—Wallace and the Sexual Selection Theory—The Sense of Smell in Butterflies and Moths—Fragrant Butterflies—Wingless Moths and their Lures to Lovers—Methods of Pairing among Butterflies and Moths—More Experiments 185 CHAPTER XI BEETLES THAT “BLUFF” The Coloration, and other Forms of Ornament in Beetles, and the Significance thereof in regard to the Sexual Selection Theory—The Courtship of Grasshoppers and their Kin—The Remarkable Ears of Locusts and Grasshoppers—The Field-cricket and the Katydid as Troubadours—The Wonderful Performances of the Cicadas—The Duels of Long-horned Locusts—Dragon flies—The May-flies’ “Dance of Death”—The Jaws of the Giant Alder-fly and their Strange Use—Some Curious Facts about Stone-flies 208 CHAPTER XII SCORPIONS, SPIDERS AND CRABS