328 NATURAL SCIENCE. Nov., 



case of certain mammals, birds, and insects, to the effects of female 

 preference. (2) The melanic forms of some butterflies, spiders, 

 lizards, birds, and mammals are also considered, by various authors, 

 to have been sexually selected. 



It is incredible enough, after all that has been written to prove 

 the " capricious action of sexual selection, fluctuating element of 

 taste, charm of novelty, etc.," that we should still find the females of 

 different species, families, orders, and sub-kingdoms concurring, during 

 untold ages, and with more than human consistency, in their approval 

 of one particular kind of ornamentation. But it becomes still more 

 incredible — if the word could be made to admit of degrees — in the 

 view of the circumstance that, as regards (i), the same parts are also 

 brightly tinted with certain saurians where it is impossible for the 

 females to see them, and respecting (2), there are dark varieties of 

 other animals that no one has hitherto ventured to attribute to sexual 

 selection. Such are, for instance, the recent and non-adaptive forms 

 of colubrine snakes, " higher animals," like Zamenis viridiflavus, vav. 

 cavbonavius. Our own species furnishes a curiously similar instance. 

 The gradual diminution of the xanthous complexion to the advantage of 

 a darker stock appears to be proceeding in various parts of the world 

 quite irrespective of climatical conditions, and yields, therefore, the 

 strongest presumptive evidence in favour of sexual selection. Here, 

 as in the other instances, the ontogeny shows that the males are the 

 first to become modified. Now, in the case of man, there are 

 exceptional facilities for observation and the a priori probability that 

 the aesthetic faculties are more highly developed than in other animals. 

 Still, among the many suppositions that have been advanced to 

 account for this displacement of the fair by a darker type, I can find 

 surprisingly little that suggests the " cumulative action of female 

 preferences." 



There are difficulties of another order. Compare the classical 

 case of the argus pheasant with that of man. No doubt the earnest- 

 ness of purpose and degree of estimation with which the females of 

 this bird may regard, for the time being, the objects of their affection 

 may be the same as with us : " le bean pour le crapaud c'est sq crapaude." 

 There is, however, a difference in kind. For personal beauty with 

 man possesses a purely extrinsic worth — it lies in the eye of the 

 beholder. But if the argus pheasants, waiving private inclinations in 

 favour of sterner motives, have dispassionately judged, as they must 

 have done, with the eye of connoisseurs and by one unvarying^ 

 standard the artistic merits of their countless generations of suitors, 

 they have set an intrinsic value on the beauty of the latter. Unless 

 this ideal striving coincides with the greatest physical vigour, it can 

 only be due to the survival of the intellectually fittest. 



However that may be, it is no hair-splitting distinction, nor is it 



iNot "approximately," Proc. Zool. Soc, 1881, p. 36S. 



