Chap. IX. Spiders. 273 



the fact that the males of certain species present two forms, 

 differing from each other in the size and length of their jaws ; and 

 tliis reminds us of the above cases of dimorphic crustaceans. 



The male is generally much smaller than the female, sometimes 

 to an extraordinary degree,™ and he is forced to be extremely 

 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 devoured, a 

 " sight which, as he adds, filled him with horror and indignation." "' 

 The Rev. 0. P. Cambridge''^ accounts in the following mannei 

 for the extreme smallness of the male in the genus Nephila. 

 " M. Vinson gives a gTaphic account of the agile way in which 

 " the diminutive male escapes from the ferocity of the female, by 

 " gliding about and playing hide and seek over her body and 

 ■' along her gigantic limbs : in such a pursuit it is evident that 

 " the chances of escape would be in favour of the smallest males, 

 " while the larger ones would fall early victims ; thus gradually 

 " a diminutive race of males would be selected, until at last they 

 " would dwindle to the smallest possible size compatible with the 

 " exercise of their generative functions, — in fact probably to the 

 " size we now see them, i.e., so small as to be a sort of parasite 

 " upon the female, and either beneath her notice, or too agile and 

 " too small for her to catch without great difittculty." 



Westring has made the interesting discovery that the males 

 of several species of Theridion'^ have the power of making 

 a stridulating sound, whilst the females are mute. The ap- 

 paratus consists of a serrated ridge at the base of the abdomen, 

 against which the hard hinder part of the thorax is rubbed ; and 

 of this structure not a trace can be detected in the females. It 

 deserves notice that several writers, including the well-known 

 araehnologist Walckenaer, have declared that spiders are attracted 

 by music.^* From the analogy of the Orthoptera and Homoptera, 



'"' Aug. Vinson (' Aran^ides des tion to Entomology,' vol. i. 1818, 



lies de la Reunion,' pi. vi. figs. 1 p 280. 



and 2) gives a good instance of the ^^ 'Proc.Zoolog. Soc' 1871, p. 621. 

 small size of the male, in Epeira ^' Theridion (^Asagena, Sund.) 



Ks^ra, In this species, as I may serratipes, 4-punctatum et giitta- 



add, the male is testaceous and the turn, ; see Westring, in Kroyer, 



female black with legs banded with ' Naturhist. Tidskrift,' vol. iv. 1842- 



red. Other eren more strikiug 1843, p. 349; and vol. ii. 1846- 



cases of inequality in size between 1849, p. 342. See, also, for other 



the sexes have been recorded species, 'Aranese Suecicie,' p. 184. 

 f Quarterly Journal of Science,' ^' Dr. H. H. van Zoutevcen, in 



1868, July, p. 429) ; but I have his Dutch translation of this work 



sot seen the original accounts. (vol, i. p. 444), has collected severa 



*' iiii'by and ):?pence, ' Introduc- cases. 



19 



