XXVI 



from the pursuit of birds on account of their distastefuhiess and yet, sy far as 

 I know, a repulsive smell has not yet been detected in them.* Ttfe odour 

 emitted by the odoriferous tufts of the males is generally very fj/mt and 

 far from being unpleasant, but is rather like that of vanilla or roses, so that 

 the cause of the distastefulness cannot be sought therein, the less sc, since 

 it emanates from the wings, which are not eaten. We have thus numerous 

 imitators taking for models species without any distastefulness recognizable 

 by us. 



" On the other hand, among the numerous mimics which appear ''^'■^re 

 (Itajahy) suddenly in swarms twice in the year are Acrcea Thalia and tht3 

 nmch rarer Eueides Pavana, which possesses the same odour-emitting ' 

 appendages at the extremity of the abdomen and the same repulsive smell 

 as the remainder of the Maracuja butterflies. Of the same nature is the 

 resemblance of the three related and similarly smelling species, Eueides 

 Aliphera, Colmiis Jidia, and Dione Jwio, of which the odoriferous power is 

 certainly possessed in the highest degree by the smallest species, although 

 this appears to have been acquired, in most part at least, subsequently. 

 Further, the strongly smelling Eueides Isabella and Heliconius Encrate 

 have either individually or together acquired a resemblance to Mechanitis 

 Lysimnia, which (apart from the extremely faint, and to us scarcely per- 

 ceptible, odour of the male) is to us inodorous; and, among the numerous 

 butterflies which sufficiently resemble the three above-named species as to 

 be occasionally mistaken for them are species belonging to the Ithoniia 

 group {MelincEU) and to the true Danaides {hycorea). 



" Thyridia and Ituna both belong to the class of cases in which 

 the two species which resemble one another appear to be equally well 

 protected by distastefulness. The former belongs to the Ithoiiiia group, 

 the distastefuhiess of which has been just referred to, and the latter 

 to the Danaides, which play the same part as models of imitating species 

 in the Old World as the Ithomias in the New. They appear even after 

 death to defy the ravages of time and the attacks of mites, &c., by virtue 

 of their distastefulness. Last year Mr. Raphael Meldola exhibited to 



* [The fact that no odour has been detected cannot be considered as conchisive 

 evidence that none is emitted. Just in the same manner as there are sounds and 

 colours both above and below the limits of our sensual ijerceptions, so there may bo 

 odours iuaiipreciable by our bense of smell. — R. J/.] 



On what authority does Prof. Delbceuf state (' Kosmos,' vol. ii., p. 100; that " the 

 Heliconidse (the subject treated of referred to Ithomia, not to Heliconius) when in 

 danger emit a disgusting fluid, which makes them the most distasteful of all food"? 

 It probably proceeded from the pen of one of the numerous followers of Bates and 

 Wallace, who so easily tread the path laboriously beaten out by these unsui-passed 

 observers of mimicry and protective resemblance. [Here follows a severe criticism 

 of Mr. A. W.Bennett's objections to tbe explanation of mimicry by natural selection ; 

 vide ' Nature,' vol. iii., p. 80.] 



