SECONDARY SEXUAL CHARACTERS 107 



eyes of the male have stalks longer than those of 

 the female (Fig. 53). In another genus of flies there 

 are horns on the head like the antlers of the stag 

 (Fig. 54). 



'In the spiders the adult males are sometimes very 

 small in comparison with the females (Fig. 55). The 

 size difference may be regarded as a secondary sexual 



FIG. 55. Male (to left) and female (to right) of a spider, Argiope aurelia. 

 (From " Cambridge Natural History.") 



character. Darwin points out, since the male is some- 

 times devoured by the female (if his attentions are 

 not desired), that his small size may be an adaptation 

 in order that he may more readily escape. But the 

 point may be raised as to whether he is small in order 

 to escape ; or whether he is eaten because he is small. 

 In one of our native spiders, Habrocestum splendida, 

 the adult males and females are conspicuously different 



