PECKHAM. 



[Vol. 1, 



Taczanowski says that A. horrida (PL III, fig. 5,) is very 

 like rugosa, and adds that he considers this species as transitory 

 between Epeira and Acrosoma. 



Cambridge remarks upon the great variability in the 

 length and direction of the spines in individuals of the same 

 species of Gasteracantha.* Vinson notices the same character 

 in regard to the color of at least one species.f That variability 

 in the spines is found also in Acrosoma, is illustrated in Plate 

 III, where figures 1 and 3 represent extreme forms of the 

 female of A. spinea, the former being found in the northern 

 and the latter in the southern 

 part of the United States. A. 

 oblonga (fig. 6) is given to show 

 the sharpness of the spines in 

 some of these species. 



The sexes in Gasteracantha 

 and Acrosoma are entirely dif- 

 ferent. The males are small, 

 sometimes very minute, and lack 

 both the spines and the brilliant 

 color of the females (fig. 10, and 

 Plate III, figs. 1, 2 and 3). In- 

 deed, they resemble the females 

 so little that for many years 

 the relations between the two 

 were undiscovered. In the 

 genus Gasteracantha, up to so 

 late a date as 1879. only two 

 males had been described, 

 against one hundred and seventy females. J 



This disparity has come about through the different habits 

 and functions of the female. Wallace has shown that among 

 insects the females often acquire protective colors which are 



Fig. 10. — Gasteracantha ruflspinosa. 

 Upper figure male, lower figure female 

 {from Marx). 



*Froc. Zool. Soc, 1879, p. 279. 



iZoe. cit., p. 241. 



t Cambridge, Proc. Zool. Soc, 1879, pp. 279 and 281. 



