180 PECKHAM. [Vol. 1, 



Throughout the great group of Myriapoda, of which hundreds 

 of specimens from all localities have passed through my 

 hands, there is not a single case, so far as I know, of the sexes 

 differing in color. And yet, many of the species, both of 

 Diplopoda and Chilopoda, are very beautifully colored. Now, 

 there is no scope in this group for the action of sexual selection, 

 because if not entirely without eyes, none of the species (except 

 perhaps Sentigera) can see to any appreciable extent. But if 

 Wallace's generalization with regard to the greater vigor of 

 the male be true, we should expect to find the males more 

 beautiful than the females, quite irrespective of powers of 

 vision. And that the males are more vigorous, at least in 

 some cases, is shown by the fact that the males of two South 

 African species of Spirostreptus, that I have in captivity, 

 certainly excel the females in activity and amorousness — the 

 last quality being, I should think, an unquestionable criterion 

 of vital force. But these males only differ from the females in 

 primary sexual features." 



SECOND PART OF MR. WALtACB'S THEORY : CORRELATION OF 

 HIGH VITALITY AND BRIGHT COLOR AMONG MALES. 



The second point in Mr. Wallace's proposition is that those 

 males that have the highest vitality have the most brilliant 

 color. In " Tropical Nature " there are named six species of 

 humming-birds in which there is a combination of unusual ac- 

 tivity and pugnacity with brilliant color. Since there are four 

 hundred and twentj^-six species of humming-birds, a large pro- 

 poi'tion of which are brightlv colored, this number is certainly 

 very low. There are also adduced five cases of birds where the 

 females are brighter than the males, in which " the males take 

 charge of and incubate the eggs while the females are almost 

 always larger and more pugnacious than the males. " * 

 Furthermore, Mr. Wallace, in " Darwinism, " speaks of the or- 

 namental plumes that arise not only in birds of paradise, but 



*Tropiciil Nutui'e, p. ^12. 



