( V ) 



Mimicry between Inedible Forms, and (4) Divergent Members 

 of Inedible Groups, The paper was illustrated by coloured 

 drawings of the species referred to. The author said : 



(1.) An objection often brought against the theory of 

 mimicry was the difficulty of imagining the first stages in 

 the production of a mimetic pattern. In reply to this Fritz 

 Miiller urged that mimicry must be supposed to have origi- 

 nated between forms that already bore considerable re- 

 semblance to each other. His contention, though hardly 

 confirmed by the instances on which he relied, is sound in 

 so far as it emphasises the fact that the process of mimetic 

 assimilation depends rather on the development of old than 

 on the starting of new features. An illustration of this is 

 afforded by a comparison of the non-mimetic butterflies, 

 Pieris locusta and P. ithaloe, with the mimetic species of the 

 closely allied genus Mylothris, and with Hellconius nianata, 

 which serves as the model for the latter ; all these being 

 neotropical forms. The whole series shows (i.) that a 

 practically perfect mimetic pattern can be evolved by gradual 

 stages without any abrupt change ; (ii.) that it is not neces- 

 sary that the forms between which mimicry originates should 

 possess considerable initial resemblance; (iii.) that so small a 

 beginning as the basal red patches on the underside of the 

 hindwing of many Pierines gives sufficient material for the 

 assimilative process to work upon. 



(2.) The feeble development of the mimetic pattern in the 

 males of this group calls for some explanation. No doubt 

 the females stand in greater need of protection, but does 

 there exist any active check on the fuller assumption of 

 mimetic patterns by the males ? The retention of the 

 original white by the latter sex has been in similar instances 

 attributed to female choice ; Mr. Wallace on the other hand 

 thinks it due to the difference of habits in the two sexes, the 

 females alone flying in company with the mimicked Heliconii. 

 But this leaves unexplained the presence of a partial mimetic 

 pattern in the male. The probability is that although on 

 the wing it may be advantageous rather than otherwise to the 

 male, as Mr. Wallace thinks, to be taken for an ordinary 

 white butterfly, yet when the insect is at rest, and settled 



