6 THE EVOLUTION OF SEX. 



more brilliant than the females ; and many male beetles fight 

 savagely for the possession of their mates. 



Passing to backboned animals, we find that among fishes 

 the males are frequently distinguished by bright colours and 

 ornamental appendages, as well as by structural adaptations for 

 combat. Thus the "gemmeous dragonet " {Callionyniiis lyrd) is 

 flushed with gorgeous colour, in great contrast to the " sordid " 

 female, and is further adorned by a graceful elongation of the 

 dorsal fin. In many cases, as in the sea-scorpion {^Cottus 

 scorpius), or in the stickleback {Gasterosteus\ it is only at the 

 reproductive period that the males are thus transformed, 

 literally putting on a wedding-garment. Every one knows, on 

 the other hand, the hooked lower jaw of the male salmon, 

 which comes to be of use in the furious charges between rivals; 

 and this is but one illustration of many structures utilised in 

 the battle for mates. In regard to amphibians, it is enough to 

 recall the notched crests and lurid colouring of our male newts, 

 and the indefatigable serenading powers of male frogs and 

 toads, to which the females are but weakly responsive. Among 

 reptiles, differences of this sort are comparatively rare, but male 

 snakes have often more strongly-pronounced tints, and the 

 scent-glands become more active during the breeding season. 

 In this, as in many other cases, love has its noisy prayer re- 

 placed by the silent appeal of fragrant incense. Among lizards, 

 the males are often more brightly decorated, the splendour of 

 their colours being frequently exaggerated at pairing time. 

 They may be further distinguished by crests and wattle-like 

 pouches ; while horns, probably used in fighting, are borne by 

 some male chamseleons. 



It is among birds, however, that the organic apparatus of 

 courtship is most elaborate. The males very generally excel in 

 brighter colours and ornaments. Beautiful plumes, elongated 

 feathery tresses, brightly-coloured combs and wattles, top-knots 

 and curious markings, occur with marvellous richness of variety. 

 These are frequently displayed by their proud possessors before 

 the eyes of their desired mates, with mingled emotions of eager 

 love and pompous vanity; or it may be to the subtler charms of 

 music that the wooers mainly trust. During the breeding 

 season, the males are jealously excited and pugnacious, while 

 some have special weapons for dealing directly with their rivals. 

 The differences between the magnificent male l)irds of paradise 

 and their sober mates, between the peacock with his hundred 



