Lastly, the feathers composing the crest in male Polish fowls resemble hackles, and differ greatly in shape from those in the crest of the female. The neck, wing-coverts, and loins {275} in the male bird are properly covered with hackles, and it would appear that feathers of this shape have spread by correlation to the head of the male. This little fact is interesting; because, though both sexes of some wild gallinaceous birds have their heads similarly ornamented, yet there is often a difference in the size and shape of feathers forming their crests. Furthermore there is in some cases, as in the male Gold and in the male Amherst pheasants (_P. pictus_ and _Amherstiæ_), a close relation in colour, as well as in structure, between the plumes on the head and on the loins. Hence it would appear that the same law has regulated the state of the feathers on the head and body, both with species living under their natural conditions, and with birds which have varied under domestication. * * * * * {276} CHAPTER VIII. DUCKS--GOOSE--PEACOCK--TURKEY--GUINEA-FOWL--CANARY-BIRD--GOLD-FISH-- HIVE-BEES--SILK-MOTHS. DUCKS, SEVERAL BREEDS OF--PROGRESS OF DOMESTICATION--ORIGIN OF, FROM THE COMMON WILD-DUCK--DIFFERENCES IN THE DIFFERENT BREEDS--OSTEOLOGICAL DIFFERENCES--EFFECTS OF USE AND DISUSE ON THE LIMB-BONES. GOOSE, ANCIENTLY DOMESTICATED--LITTLE VARIATION OF--SEBASTOPOL BREED. PEACOCK, ORIGIN OF BLACK-SHOULDERED BREED. TURKEY, BREEDS OF--CROSSED WITH THE UNITED STATES SPECIES--EFFECTS OF CLIMATE ON. GUINEA-FOWL, CANARY-BIRD, GOLD-FISH, HIVE-BEES. SILK-MOTHS, SPECIES AND BREEDS OF--ANCIENTLY DOMESTICATED--CARE IN THEIR SELECTION--DIFFERENCES IN THE DIFFERENT RACES--IN THE EGG, CATERPILLAR, AND COCOON STATES--INHERITANCE OF CHARACTERS--IMPERFECT WINGS--LOST INSTINCTS--CORRELATED CHARACTERS. I will, as in previous cases, first briefly describe the chief domestic breeds of the duck:--