22 



PECKHAM. 



[Vol. 1. 



inconsiderable, and while even in these cases the female is but 

 little more conspicuous than the male, in spiders there are 



numerous species in which the 

 female is decked in the most 

 gaudy hues, her body being at 

 the same time protected by 

 strong, sharp spines, while the 

 smaller male is unarmed and 

 comparatively inconspicuous.* 

 (Figs. 1 and 2.) The spiders 

 to which we refer belong to the 

 genera Gasteracantha, Acrosoma, 

 Fhoronocidia and others, includ- 

 ing possibly 250 species distri- 

 buted over all parts of the 

 world. The differences between 

 the males and females are shown 

 in Plate III. Only a few males 

 are described in this group, but 

 they all agree in the peculiari- 

 ties mentioned. 



The perplexing fact in 

 this connection is that 

 while the females at first 

 resemble the males, it is 

 only while they are quite 

 young, since when they 

 are from a quarter to a 

 third grown they begin to 

 assume the adult form 

 and color, and it seems as 

 though characteristics de- 

 veloping so early should 



-Gasteracantha crepidophora, ieinale 



(from Cambridge.) have been transmitted to 



Fig. 1.— Gasteracantha rufosplnasa. 

 Upper figure, male enlarged seven times ; 

 lower flgurer female, enlarged four 

 times (from' Marx.) 



1 A seeming exception to this rule is G. Cowani, i? , described in Proc, Zool. 

 'Soc, 1882, p. 766. As this case was sufficient to invalidate our generalization we wrote 

 to Mr. Butler, asking him to re-examine the spider in question to make sure that it 



