Il8 THOS. MONTGOMERY, JR. 



alternating with batches of male eggs only ; I did not have a 

 sufficient number of cocoons from any one female to determine 

 what is the regularity of this succession. Or again both kinds 

 of eggs may occur in the same cocoon, and perhaps future ob- 

 servations will show that the first cocoons contain only large (or 

 small) eggs, the next succeeding eggs of both kinds, and the 

 last cocoons only small (or large) eggs. 



Whether this dimegaly is true sexual dimorphism can be 

 decided only by examining the genital organs of the hatching 

 spiderlings since there are no external sexual differences apparent 

 in the young, which would require much labor ; or by raising all 

 the spiderlings to maturity, a method that would require still 

 more time and patience. But one of these methods must be 

 tried in order to finally demonstrate whether this is true sexual 

 dimorphism of the eggs. 



If the small and large eggs of Theridium are really male and 

 female eggs, and it must be admitted that there is a probability 

 of this, then here is another instance of two kinds of eggs to be 

 added to those already known, namely, the cases of the Aphids, 

 Rotatoria and Dinophihts apatris. Adult sexual differences in size 

 are very marked in many spiders, the male is probably always 

 somewhat the smaller, and in many species, particularly among 

 the Argiopidse, Theridiidas and Thomisidae the disparity in size 

 of the sexes is most striking. It would be of interest to examine 

 this point in the case of the common orb-weaver Argiope 

 cophinaria (Walck.), where the male may be less than one 

 fiftieth the volume of the grown female, here if any where there 

 should be marked dimorphism of the eggs ; and in species of the 

 genus Acrosoma, The common Epcira labyrinthea Hentz would 

 be especially favorable because it places its cocoons in a string 

 in the order of their making. 



