310 THE DESCENT OF MAN. 



Myriapoda. In neither of the two orders in this class, 

 the millipedes and centipedes, can I find any well-marked 

 instances of such sexual differences as more particularly 

 concern us. In (lloweris Ihnbata, however, and perhaps 

 in some few other species, the males differ slightly in color 

 from the females; but this Glomeris is a highly variable 

 species. In the males of the Diplopoda, the legs belong- 

 ing either to one of the anterior or of the posterior seg- 

 ments of the body are modified into prehensile hooks 

 which serve to secure the female. In some species of 

 lulus the tarsi of the male are furnished with membranous 

 suckers for the same purpose. As we shall see when we 

 treat of insects, it is a much more unusual circumstance, 

 that it is the female in Lithobius, which is furnished with 

 prehensile appendages at the extremity of her body for 

 the male.* 



*\Valckenaer et P. Gervais, "Hist. Nat. des Insectes; Apteres," 

 toin. iv, 1847, pp. 17, 19, 68. 



