72 Dr. F. A. Dixey on the Relation of 



exhibited by P. pit aloe; but wliereas in Mylothris the 

 rnain red streak of the hind wing arises from the internal 

 and median basal red, and is central (Fig. 5, cd), in 

 Hefsjyerocharis it results from a development of the pre- 

 costal and costal red patches, and occupies the correspond- 

 ing regions of the wing (Fig. 12, a, h). The precostal 

 red is undeveloped in Mylothris, and the median red is 

 undeveloped in Hesperocharis. One result of this 

 is that in the latter form the relative position of the main 

 yellow and red streaks is reversed ; notwithstanding 

 which the general resemblance to Mylothris is consider- 

 able, and the difference would very probably remain 

 undetected by many insectivorous animals. The present 

 point has already been noticed by me elsewhere.* I draw 

 attention to it here simply because it affords another 

 illustration of the gradual growth of mimetic patterns 

 from an original non-mimetic form.-f 



III. Recipeocal Mimicry between Inedible Forms. 



In the previous communication to the Entomological 

 Society! of which I have already made mention, I drew 

 attention to certain facts which I am now able to illustrate 

 by PI. v., Figs. 13 and 14, representing the undersides of 

 a Pierine [Pereute levcodvosime) and a Heliconius {H. mel- 

 pomene) respectively. Both Heliconius and Pereute are, 

 it will be seen, furnished with basal red spots, and this is 

 the case with very many of the Heliconii and their 



* Trans. Ent. Soc. Lond., 1894, p. 286. 



t Throughout the foregoing remarks, F. plialor and P. Jocusta $ , 

 have been spoken of as non-mimetic forms. This is undoubtedly 

 the case with P. jilialoo, but it is perhaps possible that even in 

 P. locusfa $ , the underside of the hindwing may have (especially 

 in darkly-coloured individuals) a certain mimetic value. The 

 underside of the hindwing in P. locuda, P. cinerea and some 

 others resembles that of IleUconius melpomene and other protected 

 species in giving the general idea of a dark wing-area with yellow 

 costal or precostal streak and basal red spots. The forewing of 

 P. locusta contains a large surface of white, but this would be 

 partly or wholly concealed in the resting position. It is true also 

 that the yellow streak and red patches do not occupy exactly 

 corresponding positions in the Pieris and the Heliconius ; but there 

 is abundant evidence to show that while affinity displays great 

 respect for the exact position on the wing of any given feature 

 of the pattern, mimicry to a large extent disregards this, and aims 

 rather at a general similarity of effect. See the instance of 

 Hesperocharia hii-landa above, and see also below, p. 74, note. 



X Trans. Ent. Soc. Lond., 1894, pp. 296, etc 



