368 THE DESCENT OF MAN. 



With several species the sexes are alike, and imitate the 

 two sexes of another species. But Mr. Trimen gives, in 

 the paper already referred to, three cases in which the sexes 

 of the imitated form differ from each other in color, and 

 the sexes of the imitating form differ in a like manner. 

 Several cases have also been recorded where the females 

 alone imitate brilliantly-colored and protected species, the 

 males retaining *^ the normal aspect of their immediate con- 

 geners.'^ It is here obvious that the successive variations 

 by which the female has been modified have been trans- 

 mitted to her alone. It is, however, probable that some of 

 the many successive variations would have been transmitted 

 to, and developed in, the males had not such males been 

 eliminated by being thus rendered less attractive to the 

 females; so that only those variations were preserved which 

 were from the first strictly limited in their transmission to 

 the female sex. We have a partial illustration of these 

 remarks in a statement by Mr. Belt; * that the males of 

 some of the Leptalides, which imitate protected species, 

 still retain in a concealed manner some of their original 

 characters. Thus in the males " the upper half of the 

 lower wing is of a pure white, while all the rest of the wings 

 is barred and spotted with black, red and yellow, like the 

 species they mimic. The females have not this white 

 patch, and the males usually conceal it by covering it with 

 the upper wing, so that I cannot imagine its being of any 

 other use to them than as an attraction in courtship, when 

 they exhibit it to the females, and thus gratify their deep- 

 seated preference for the normal color of the order to which 

 the Leptalides belong. '^ 



Bright Colors of Caterpillars, While reflecting on the 

 beauty of many butterflies it occurred to me that some 

 caterpillars were splendidly colored; and as sexual selection 

 could not possibly have here acted, it appeared rash to 

 attribute the beauty of the mature insect to this agency, 

 unless the bright colors of their larvae could be somehow 

 explained. In the first place, it may be observed that the 

 colors of caterpillars do not stand in any close correlation 

 with those of the mature insect. Secondly, their bright 

 colors do not serve in any ordinary manner as a protection. 



* " The Naturalist in Nicaragua," 1874, p. 385. 



