BEDROCK 



are confined to one sex ; but, as regards the males, they afford a 

 most excellent test. Furthermore, Mr. Lamborn has bred two 

 families of Am. psyttalea, and in both the butterflies were nothing 

 but psyttalea. 



The pattern of niavius (Fig. 1) and its mimic anthedon (Fig. 6) 

 stands widely apart from those of the other models and mimics 

 represented on Plate III. The principal marking of the former 

 spreads over both wings, but in the latter it is confined to the hind 

 wing. Intermediates between niavius and the other models are 

 unknown, but are not very uncommon between anthedon and the 

 other mimics. A good example strongly on the anthedon side of 

 intermediate is represented in Fig. 7, another strongly on the dubia 

 side in Fig. 11, and its intermediate offspring in Figs. 12, 13 and 14. 

 The pattern is continued on to the fore wing in these last four 

 examples as a brown, and not as a white streak, and even in the 

 original of Fig. 7 the corresponding part of the fore wing is of a pale 

 brownish shade. Mr. Lamborn has twice bred from a female with 

 the pattern shown in Fig. 11. The entire smaller family is repre- 

 sented in Figs. 12 — 16, and in both it and the other far larger 

 family the dubia offspring strongly inherited the intermediate 

 tendency of the parental pattern. The intermediate pattern 

 behaved in heredity as a definite whole, and did not split up as 

 though it were a hybrid (or heterozygote). It is reasonable to 

 conclude that such specimens as those shown in Figs. 7 and 11 are, 

 like trimeni, leighi and dionysus, relatively rare but persistent 

 ancestral steps showing us how, under the guidance of selection, 

 the wide gap between the pattern of anthedon and that of dubia has 

 been crossed. 



It may be safely concluded from the consideration of these two 

 interesting and complicated examples of mimicry that the mimetic 

 resemblance has not been produced from the original non-mimetic 

 form by a sudden mutation, but has been the result of a series of 

 transitional steps, some of which are still preserved. 



56 



