Mimetic Patterns to the Original Form. 67 



Pieris we get a great lightening of the general tone of 

 colour, without however losing the essential features now 

 referred to. In P. ijhaloe for instance, also a non- 

 mimetic Pieris from the same neotropical region, we have 

 as it were an attenuated and washed-out version of the 

 scheme of mai-king seen on the hindwing of P. locusta. 

 Here (Fig. 2) are visible the same basal red patches, 

 though now confined to the precostal and internal spaces ; 

 the same pale costal streak and central area, now in most 

 specimens white rather than yellow ; and on either side 

 of the latter the same two dark shades, now reduced to 

 a pair of brownish streaks. From either of these types 

 to the well-known Heliconine form here represented by 

 Heliconius niimata (Fig. 11), seems a sufficiently long 

 step ; nor is it at first sight apparent that there is any- 

 thing in common between the former and the latter 

 schemes of coloration. Nevertheless, while it will be 

 allowed on the one hand that the female of Mylothris 

 pyrrha (Figs. 9, 10) presents a very good imitation of 

 H. numata, it can be shown on the other hand that this 

 last-named Pieriue owes its mimetic features to a simple 

 development of characters already possessed by the 

 other Pierine forms just spoken of, to which it is closely 

 allied. 



In order to make this apparent, it will be necessary to 

 refer to some of the other neotropical species of the 

 same genus Mylothris. This interesting little group, 

 comprising besides M. jjyrrha the closely related M. 

 malenl-a, M. lypera, and M. lorena, has been more than 

 once spoken of by Mr. Wallace* as affording an instance 

 of mimetic females associated with males of the ordinary 

 white type of Pierine coloration. It is quite true that 

 all the males throughout the group exhibit on their upper 

 surfaces nothing but the ordinary white character ; Mr. 

 Wallace, however, does not mention the curious fact 

 that the same males universally show ou the under 

 surface, though in varying degrees, an approach towards 

 the Heliconine pattern that is so completely imitated 

 by their mates. These partially developed features on 

 the under surface of the males enable us to trace the 

 history of the growth of the mimetic pattern. 



Let us take the underside of the male of Mylothris 



° " Tropical Nature," 1878, p. 204 ; "Darwinism," 1889, p. 271. 



