4 



( 14 ) 



case, because the species would be in what I have called a 

 state of mimetic equilibrium. It is also obvious that if 

 mimetic approach be possible between two such species, then 

 it must necessarily be simultaneous. 1 therefore feel entitled 

 to claim that I was fully justified in asserting simultaneous 

 approach to be an essential feature of the hypothesis of 

 Reciprocal Mimicry, and that I was also justified in treating 

 Alternating Mimicry as a conception differing radically from it." 



Wednesday, November 4th, ^908. 



[Ixxvi 

 Stick Insect. — Mr. R. Shelford showed a " Stick " insect 

 — apparently a new species of the genus Menexenus — bred 

 parthenogenetically by Mr. H. Main. 



[Ixxviii 

 The Double or Combined Aposeme. — Dr. F. A. Dixey ex- 

 hibited specimens of Heliconius amphitrite, Riff., and H. chari- 



thonia, Linn. ; also a coloured drawing of II. hermathena., 

 Hew. He remarked that each of the first two species showed 

 a distinct and well-marked aposeme or warning character ; 

 each of them, and especially the first, belonging to an exten- 

 sive mimetic assemblage. In the third species these two 

 distinct aposemes were combined. 



These specimens illustrated the fact that a conspicuous and 

 distasteful form might acquire a new aposeme without relin- 

 quishing its old one, such an intermediate form pi-esumably 

 sharing in the protection afforded by the aposematic forms on 

 each side of it, while the separate aposemes which it exhibited 

 were not mutually protective. This would give the inter- 

 mediate form an advantage over the extremes, provided that 

 all were found in the same district, or (which was not quite 

 the same thing) were exposed to the attacks of the same 

 enemies. In this particular case the facts of geographical 

 distribution made such a protective relation between the 

 forms unlikely ; but the series afforded a good illustration of 

 the actual existence of what he had before spoken of as the 

 " double " or " combined " aposeme. 



