126 Mr. G. A. K. Marshall on Diaposematism, ivith reference 



for a very considerable time from the Eastern Tirumalas. 

 We have therefore no reason for assuming that the ob- 

 viously recent intruder, T. petiverana, must have been the 

 direct progenitor of the Melindas. 



The more recent intrusion of petiverana must also be 

 inferred if we apply Professor Poulton's test, namely, a 

 comparison of the mimetic effect produced by the respective 

 forms. In spite of its abundance and widespread occur- 

 rence in Tropical Africa petiverana has not yet succeeded 

 in producing a really close mimic, though there are two or 

 three species which present a generalised resemblance to 

 it ; whereas all three Melindas have entered into a very 

 close mimetic association with some particular species, 

 thus indicating that they have been resident in the country 

 for a longer period. 



There seems to be no justification for assuming that 

 Mclinda has been directly derived from any particular 

 species of Asiatic Tirumala as we now know it. But 

 with regard to the pale patch in the hind-wing referred 

 to by Mr. Neave, we may note that it occurs in several 

 Eastern Tirumalas, such as various forms of limniace and 

 melissa, choaspes, etc. ; its appearance being very similar to 

 what we find in M. formosa. Wherefore the statement 

 that this character must be a "new and non-ancestral 

 development" in the last species cannot be reasonably 

 maintained. Moreover, this type of marking is very 

 common among Asiatic Danaines and is particularly 

 characteristic of the African forms. 



As to the pointed fore-wing of M. formosa, it is true 

 that no Tirumala exhibits a similar shape ; but this again 

 is far from being an unusual character among Eastern 

 Danaines, and in the genus Nasuma it has attained an 

 even greater development than in Melinda. An elongated 

 fore-wing is also a very common feature among the African 

 species and is to be found in a considerable number of 

 Amauris. It is by no means clear why these slow-flying 

 butterflies should have so largely adopted this pointed 

 form of wing ; but it seems not improbable that the cause 

 which has produced this effect in Amauris has also operated 

 on the Melindas during their prolonged isolation from their 

 Eastern progenitors. This view is indirectly supported by 

 the following facts. 



Mr. Neave has pointed out that in the Abyssinian sub- 

 species 31. formosa ncumanni the fore-wings are slightly 



