OF ARTS AND SCIENCES. 153 



self quotes : in almost all of them, both males anrl females are of some 

 shade of blue ; in comparatively few, the males are blue and the femnles 

 brown ; in exceedingly few, both sexes are brown ; and the very fact 

 that they are familiarly known as " Blues" is a popular recognition of 

 the prevailing color. In the group of Skippers to which H. Brettus 

 belongs (^Aslyn), tiie prevailing colors, at least in the temperate zones, 

 are certainly tawny and black, or brown ; the latter, marginal. This 

 is the case with the male of H. Brettns, while the female diverges 

 from the type in becoming wholly brown. In Jusonlades TiiniHS, 

 where we sometimes have a black female, it is more ditficult to decide 

 what should be considered tiie normal color, owing to diversity of view 

 upon the relationship of many of the Swallow-tails ; but. to judge only 

 from those agreed by all to be most nearly allied to it, there can be no 

 question whatever that the striped char.icter prevails. 



It will also be noticed, in this last case and others given, that wher- 

 ever partial antigeny or dimor[)liism is confined to one sex, it is always 

 to the female : there seems to be no exception to this rule. In these 

 instances, on my hypothesis, half of the females depart from the type ; 

 on Darwin's, half of the females, and ail of the males. But if, on Dar- 

 win's theory, sometimes one-half, and sometimes three-quarters of a 

 species has diverged from the type, why does it never happen that 

 only one-fourth of the sjiecies diverges ? This seems to be a very per- 

 tinent and damaging inquiry. 



The instances given by Darwin, which strongly sustain his view, 

 are drawn from specimens of the Sotith American genus Epicalia, 

 found in the rich cabinet of Mr. Bates. The facts, as stated by him. are 

 these : There are twelve sjjecies of the genus discussed by him ;* of 

 these, nine have gaudy males and plain females ; one has plain male 

 and plain female ; and two have gaudy males and gauily females. The 

 plain females, he adds, '' resemble each other in their general type of 

 coloration, and likewise resemble both sexes in several allied genera, 

 found in various parts of the world." To examine this case fairlv 

 would need a large collection of exotic butterflies. If we confine our- 

 selves to Epicalia, we evidently cannot say whether the gaudy or the 

 plain coloring be normal : there would be less variation from the 

 standard on the supposition that the gaudy were the normal t3'pe, and 

 in this case it is the female which has departed from the type ; but the 

 difference is not enough to form an objection. It is only when we 

 look outside of Epicalia that judgment seems to lean toward Darwin's 



* Kirby, in his last general catalogue, gives fifteen. 



