184 THE entomologist's record. 



On this view mimetic interchange would never be mutual and 

 simultaneous, but would only result from a complete reversal of the 

 relative dominance of the two species during the production of the 

 mimetic resemblance. For this process he had suggested the name of 

 " Alternate Mimicry." The author was also compelled to reject entirely 

 Dr. Dixey's neAV hypothesis as to the " function of the double 

 aposema," because it completely left out of consideration the differ- 

 ences and resemblances between the various forms regarded from the 

 standpoint of general facies ; he contended that resemblance in general 

 effect was of the first importance in considering mimetic relationship, 

 and that this new hypothesis Avas liable to be extremely misleading on 

 account of the exaggerated significance which it attached to the merely 

 partial resemblance which might be said to exist between two species 

 possessing a single conspicuous feature in common, but differing 

 markedly in other respects. Moreover, not only was the theoretical 

 position of "Reciprocal Mimicry "very unsatisfactory and unconvincing, 

 but, further, the cases which had been cited as proving its actual 

 occurrence in nature appeared open to serious criticism. For, while in 

 some cases the facts did not appear to justify the assertion that an 

 interchange had taken place, in the others such an interpretation 

 involved many difficulties which disappeared when the mimetic 

 phenomena were interpreted as being due to the simple mimicry of 

 one form by another. 



Mr. S. A, Neave said that as a result of his field experience 

 in Afi'ica, he was unable to accept the theory as to the function of 

 " double aposemes," but he did not mean thereby to imply that he 

 rejected every case of " Reciprocal Mimicry-." He suggested that 

 " Alternate Mimicry " might not be so uncommon a phenomenon as 

 Mr. Marshall appeared to think. 



Mr. J. W. Tutt asked whether Mr. Marshall really knew a single 

 instance in which two species, supposed to carry different aposemes, 

 lived in the same place with another species that showed the 

 aposemes of these species, and occurred with them at the same time. 

 In his exhibit Mr. Marshall showed two species with different aposemes 

 occurring in Peru, together with the presumed species showing the 

 double aposeme which he noted "did not occur within 1000 miles 

 of Peru ; " was there no instance known in nature which illustrated 

 the point at issue, and so removed the question from the rank of mere 

 theory ? Mr. Marshall said that such a case was not known to him. 



Butterflies in Switzerland in 1908. 



By J. N. KEYNES, M.A., D.Sc, F.E.S., and G. L. KEYNES. 

 (Concluded from p. 102). 

 It is always interesting to work over this familiar ground, but we made 

 few observations at Berisal of special importance. The small bright form 

 of Lowela {ChrywiAanus) alciphron var. (jordbts was to be found on the 

 Ganter road, but it was scarce ; Pleheius. zep/iynis var. lycidas, on the 

 other hand, though somewhat scarce in its special locality above the 

 Second Refuge, was to be found sparingly on both sides of this road 

 from the Ganter bridge to below the Refuge, and it was for the most 

 part in excellent condition. It is perhaps a fortunate thing for the 

 welfare of the species that its range is apparently becoming less 



