SPIDERS. 269 



of the genus to which the species belong; but Mr. Bladcwall 

 thinks that, as a general rule, it is the male; and Canestrini" re- 

 marks that in certain genera the males can be specifically dis- 

 tinguished with ease, but the females with great difficulty. I am 

 Informed by Mr. Blackwall that the sexes whilst young usually 

 resemble each other; and both often undergo great changes in 

 color during their successive moults, before arriving at maturity. 

 In other cases the male alone appears to change color. Thus 

 the male of the above bright-colored Sparassus at first resembles 

 the female, and acquires his peculiar tints only when nearly 

 adult. Spiders are possessed of acute senses, and exhibit much 

 intelligence; as is well known, the females often show the strong- 

 est affection for their eggs, which they carry about enveloped 

 in a silken web. The males search eagerly for the females, and 

 have been seen by Canestrini and others to fight for possession of 

 them. This same author says that the union of the two sexes 

 has been observed in about twenty species; and he asserts posi- 

 tively that the female rejects some of the males who court her, 

 threatens them with open mandibles, and at last after long hesi- 

 tation accepts the chosen one. From these several considera- 

 tions, we may admit with some confidence that the well-marked 

 differences in color between the sexes of certain species are the 

 results of sexual selection; though we have not here the best 

 kind of evidence, — the display by the male of his ornaments. 

 From the extreme variability of color in the male of some species, 

 for instance of Theridion lineatum, it would appear that these 

 sexual characters of the males have not as yet become well fixed. 

 Canestrini draws the same conclusion from the fact that the 

 males of certain species present two forms, differing from each 

 other in the size and length of their jaws; and this reminds us 

 of the above cases of dimorphic crustaceans. 



The male is generally much smaller than the female, some- 

 times to an extraordinary degree,™ and he is forced to be ex- 

 tremely cautious in making his advances, as the female often 

 carries her coyness to a dangerous pitch. De Geer saw a male 

 that "in the midst of his preparatory caresses was seized by the 

 "object of his attentions, enveloped by her in a web and then de- 



1° This author has recently published a valuable essay on the 'Car- 

 atterl sessuali secondaril degli Arachnid!,' In the 'Atti della Soc. 

 Veneto-Trentina di Sc. Nat. Padova, vol. 1. Fasc. 3, 1873. 



-" Aug-. Vinson ('Araneides des lies de la Reunion,' pi. vi. figs. 1 and 

 2) gives a good instance of the small size of the male, in Epeira nigra. 

 In this species, as I may add, the male is testaceous and the female 

 black with legs banded with red. Other even more striking cases of 

 inequality in size between the sexes have been recorded ('Quarterly 

 Journal of Science,' 1868, July, p. 429); but I have not seen the origi- 

 nal accounts. 



