306 THE DESCENT OP MAN. 



peror, orange-tip, &c. (Apartiira Iris and Anthocharis carda- 

 mines), the sexes differ either greatly or slightly in color. No lan- 

 guage suffices to describe the splendor of the males of some tropi- 

 cal species. Even within the same genus we often find species 

 presenting extraordinary differences between the sexes, whilst 

 others have their sexes closely alike. Thus in the South American 

 genus Bpiealia, Mr. Bates, to whom I am indebted for most of the 

 following facts, and for looking over this whole discussion, in- 

 forms me that he knows twelve species, the two sexes of which 

 haunt the same stations (and this is not always the case with 

 butterflies), and which, therefore, cannot have been differently af- 

 fected by external conditions.^ In nine of these twelve species the 

 males rank amongst the most brilliant of all butterflies, and differ 

 so greatly from the comparatively plain females that they were 

 formerly placed in distinct genera. The females of these nine 

 species resemble each other in their general type of coloration; 

 and they likewise resemble both sexes of the species in several 

 allied genera, found in various parts of the world. Hence we 

 may infer that these nine species, and probably all the others of 

 the genus, are descended from an ancestral form which was col- 

 ored in nearly the same manner. In the tenth species the female 

 still retains the same general coloring, but the male resembles 

 her, so that he is colored in a much less gaudy and contrasted 

 manner than the males of the previous species. In the eleventh 

 and twelfth species, the females depart from the usual type, for 

 they are gaily decorated almost like the males, but in a somewhat 

 less degree. Hence in these two latter species the bright colors 

 of the males seem to have been transferred to the females; whilst 

 in the tenth species the male has either retained or recovered the 

 plain colors of the female, as well as of the parent-form of the 

 genus. The sexes in these three cases have thus been rendered 

 nearly alike, though in an opposite manner. In the allied genus 

 Eubagis, both sexes of some of the species are plain-colored and 

 nearly alike; whilst with the greater number the males are deco- 

 rated with beautiful metallic tints in a diversified manner, and 

 differ much from their females. The females throughout the 

 genus retain the same general style of coloring, so that they re- 

 semble one another much more closely than they resemble their 

 own males. 



In the genus Papilio, all the species of the iEneas group are 

 remarkable for their conspicuous and strongly contrasted colors, 

 and they illustrate the frequent tendency to gradation in the 

 amount of difference between the sexes. In a few species, for 



'^ See also Mr. Bates's paper in 'Proc. Ent. Soc. of Philadelphia,' 

 1865, p. 206. Also Mr. Wallace on the same subject, in regard to 

 Diadema, In 'Transact. Bntomolog. Soc. of London,' 1869, p. 278. 



