318 LESSONS FROM NATURE. [CHAP. X. 



ring-ouzel (T. torquatus) differs less, and the female common 

 thrush ( T. musicus) hardly at all from their respective males ; 

 yet all build open nests. On the other hand, the not very 

 distantly-allied water-ouzel (Cinclus aquaticus) builds a domed 

 nest, and the sexes differ about as much as in the case of the 

 ring-ouzel. The black and red grouse (Tetrao tetrix and T. 

 scotieus) build open nests, in equally well-concealed spots, 

 but in the one species the sexes differ greatly, and in the 

 other very little.&quot; He also points out (vol. ii. p. 199) it is a 

 very strange and unlikely circumstance, if the females have 

 been rendered dull-coloured by the destruction of the brightly- 

 coloured (although all the individuals of the species tend to 

 be bright), that not only the females, but the young males 

 also, are always, or almost always, dull-coloured like their 

 mothers a quite unaccountable condition. 



As to insects, it is well known many butterflies benefit by 

 mimicking other kinds. Now in certain species the females 

 are brilliant mimics, but the males are dull. This seems to 

 conflict with the hypotheses of both Mr. Darwin and Mr. 

 Wallace. For the brilliancy is on the part of the supposed 

 selector according to Mr. Darwin, who admits &quot; it cannot be 

 supposed that the males have been kept dull-coloured by the 

 females rejecting the individuals which were rendered as 

 beautiful as themselves ;&quot; nor, as he observes, can we under 

 stand how Mr. Wallace s &quot; natural selection &quot; could have 

 kept the males dull, &quot; for it would surely not have been in 

 any way injurious to each individual male to have partaken 

 by inheritance of the protective colours of the female, and 

 thus to have had a better chance of escaping destruction &quot; 

 (vol. i. p. 414). Dragon-flies are very often brilliantly 

 coloured, and the males of some of the Agrionidde are blue, 

 with black wings, while the females are green, with colourless 

 wings. In Agrion Ilaniburii, however, &quot; these colours are 

 exactly reversed in the two sexes.&quot; Surely neither Mr. 

 Wallace s nor Mr. Darwin s hypothesis will account for this 

 singular interchange. Certainly it is incredible that females 

 of one species should have persistently preferred such 



