Crest, origin of, in Polish fowls.
Crests, of birds, difference of, in the sexes; dorsal hairy, of mammals.
Cricket, field-, stridulation of the; pugnacity of male.
Cricket, house-, stridulation of the.
Crickets, sexual differences in.
Crinoids, complexity of.
Crioceridae, stridulation of the.
Croaking of frogs.
Crocodiles, musky odour of, during the breeding season.
Crocodilia.