146 THE MALAYAN PAPILIONIDJE AS 



these distinct forms breed independently, and are never 

 reproduced from a common parent, they must be con- 

 sidered as separate species, contact without intermix- 

 ture being a good test of specific difference. On the 

 other hand, intercrossing without producing an inter- 

 mediate race is a test of dimorphism. I consider, 

 therefore, that under any circumstances the term 

 " variety " is wrongly applied to such cases. 



The Malayan Papilionidas exhibit some very curious 

 instances of polymorphism, some of which have been 

 recorded as varieties, others as distinct species; and 

 they all occur in the female sex. Papilio Memnon 

 is one of the most striking, as it exhibits the mixture 

 of simple variability, local and polymorphic forms, all 

 hitherto classed under the common title of varieties. 

 The polymorphism is strikingly exhibited by the fe- 

 males, one set of which resemble the males in form, 

 with a variable paler colouring ; the others have a 

 large spatulate tail to the hinder wings and a distinct 

 style of colouring, which causes them closely to resem- 

 ble P. Coon, a species having the two sexes alike and 

 inhabiting the same countries, but with which they have 

 no direct affinity. The tailless females exhibit simple 

 variability, scarcely two being found exactly alike even 

 in the same locality. The males of the island of Borneo 

 exhibit constant differences of the under surface, and 

 may therefore be distinguished as a local form, while 

 the continental specimens, as a whole, offer such large 

 and constant differences from those of the islands, that 

 I am inclined to separate them as a distinct species, to* 



