Sex Ratio of an Aranead 



437 



ovaries from testes, for each is simply a small paired chord of 

 germ cells of an early generation. But careful comparisons dem- 

 onstrate that there are two constant forms of the newly hatched 

 spiderlings, with the following differences. 



1 Individuals which have the abdomen wider and deeper, 

 with the dorsum much more strongly arched and the pedicel 

 placed further back. In such individuals the abdomen is almost 

 always distinctly larger. These are females. 



2 Individuals which have the abdomen narrower and less 

 deep, with the dorsum only moderately arched or not infrequently 

 flattened or even indented. Such individuals have in almost all 

 cases the abdomen smaller. These are males. 



2CX)2A 



6" 



2002} 



2003E ( \ f 



2OO3J 



201 6 J 



o 



o 



o 



Fig. 2 



Intermediates do not occur between these two groups. In Fig. 

 2 I have illustrated such differences by showing in outline the 

 abdomina of spiderlings from several cocoons. To the left is the 

 number of the particular cocoon, and on a line with it outlines of 

 the]abdomina of the largest and smallest females, and of the largest 

 male of that cocoon, each abdomen shown on lateral and ventral 

 view. It is hardly necessary to add that plane drawings cannot 



