No. 1.] SEXUAL SELECTION IN SPIDERS. 23 



both sexes. After a good deal of consideration we are 

 inclined to believe that in the early history of the group 

 the male and female both possessed some such form and 

 color as is now seen in the adult male, and in the first few 

 moults of the female; and that afterwards the adult female, 

 probably on account of some change in habits, varied toward 

 her present size, form and color under the action of natural 

 selection. " As variations occurring late in life," says Darwin, 

 "and transmitted to one sex alone, have incessantly^ been taken 

 advantage of and accumulated through sexual selection in re- 

 lation to the reproduction of the species ; therefore it appears, 

 at first sight, an unaccountable fact that similar variations have 

 not frequently been accumulated through natural selection, in 

 relation to the ordinary habits of life. If this had occurred 

 the two sexes would often have been differently modified, for 

 the sake, for instance, of capturing prey or of escaping from 

 danger. Differences of this kind between the two sexes do oc- 

 casionally occur, especially in the lower classes. But this im- 

 plies that the two sexes follow different habits in their struggles 

 for existence, which is a rare circumstance with the higher 

 animals."^ 



The other supposition open to us, namely, that the varia- 

 tion from the male form began in young females and were sex- 

 ually limited from the first, is improbable, in view of the mass 

 of evidence that variations before maturity are inherited by 

 both sexes equally. The habits of the female,' standing nearly 

 all the time exposed in the web, give the clue to the occasion of 

 her modification. The habits of the male being different, he 

 is left unmodified ; he is usually found in less exposed posi- 



was a male and not a female. Mr. Pooook, who is now in charge of the Arachnkla in 

 the British Museum, responded as follows : 



British Museum (Natural History), London, March 28, 1889. 



You are quite right in supposing that Mr. Butler fell into error in describing 

 his specimens of this species as being males. They are in reality females. The 

 distal segments, however, of the palpi are considerably wider than the preceding, and 

 no doubt the mistake arose from a superficial examination of this appendage. 



1 Descent of Man, p. 241. 



