The Descent of Man

haps entailing more important changes of
structure, than in any other class of animals. I
shall, therefore, treat the subject at considerable
length. Male birds sometimes, though rarely,
possess special weapons for fighting with each
other. They charm the female by vocal or instrumental
music of the most varied kinds. They
are ornamented by all sorts of combs, wattles,
protuberances, horns, air-distended sacks, topknots,
naked shafts, plumes and lengthened
feathers gracefully springing from all parts of
the body. The beak and naked skin about the
head, and the feathers, are often gorgeously
coloured. The males sometimes pay their court
by dancing, or by fantastic antics performed
either on the ground or in the air. In one instance,
at least, the male emits a musky odour,
which we may suppose serves to charm or excite
the female; for that excellent observer, Mr.
Ramsay (1. 'Ibis,' vol. iii. (new series), 1867, p.
414.), says of the Australian musk-duck (Biziura
lobata) that "the smell which the male emits