574 Professor E. B. Pou.lton on Mr. Thayer's 



explanation may well be that it is advantageous to direct 

 attention to the wings rather than the vital parts ; but it 

 is precisely in these groups that the black body, and some- 

 times the head, are so often marked with white or red. A 

 bright red or orange collar is found in several species. 

 Furthermore, it must be reuiembered that the body being 

 moved much less rapidly than the wings during flight is 

 more easily seen. The black and wdiite apical area of the 

 fore-wing may help to conceal, as Mr. Thayer supposes, 

 under certain conditions, but the numerous examples of 

 injuries at this very spot, figured in Plates IX and XI of 

 our Transactions for last year, strongly support the hypo- 

 thesis that it is directive, and diverts the stroke of the 

 attacking enemy from the body. 



Apart from the suggested interpretation of mimetic 

 resemblance, which I believe to be untenable, Mr. Thayer's 

 suggestions supplement and complete rather than oppose 

 existing hypotheses. The words he uses of the wasp may 

 in fact be employed of the skunk, and the well-known 

 distasteful Rhopalocerous groups, etc. The colours may 

 not be conspicuous to enemies at a great distance, "yet. 

 when seen they may well profit by the pattern's recogniz- 

 ability." We have rather insisted on this latter fact and 

 its advantage, and Mr. Thayer has done us good service 

 in calling attention to the other aspect of the appearance. 

 Ideas not dissimilar to those of Mr. Thayer's upon 

 warning colours have for some time crossed my mind. 

 Thus last year I suggested as regards the abundant, much- 

 mimicked Limnas chrysippus, that its desert form dorijJj^us 

 {Idugii) " is a development in a procryptic direction in areas 

 where the struggle " is especially severe (Trans. Ent. Soc. 

 Lond., 1902, p. 475). 



Furthermore, the idea has often forced itself upon me 

 that the ground colour of the type form of this butterfly, as 

 well as of the Ethiopian Acnvinie and Lycid beetles, may, 

 under certain conditions and at a certain distance, become 

 procryptic against the prevalent reddish tinge of the soil 

 of Africa. 



The author's suggestions of the resemblance of butterfly 

 patterns in general to flower-masses and the shadow-depths 

 between them ; of the under-sides of Grapta and the 

 upper-sides of many moths representing dead leaves lying 

 on the ground and casting such shadows as they would 

 throw at their small distance from it ; of the concealing 



