ILLUSTRATIVE OF NATURAL SELECTION. 147 



which the name P. Androgeus (Cramer) may be ap- 

 plied. We have here, therefore, distinct species, local 

 forms, polymorphism, and simple variability, which 

 seem to me to be distinct phenomena, but which have 

 been hitherto all classed together as varieties. I may 

 mention that the fact of these distinct forms being one 

 species is doubly proved. The males, the tailed and 

 tailless females, have all been bred from a single group 

 of the larvae, by Messrs. Payen and Bocarme, in Java, 

 and I myself captured, in Sumatra, a male P. Memnon, 

 and a tailed female P. Achates, under circumstances 

 which led me to class them as the same species. 



Papilio Pammon offers a somewhat similar case. 

 The female was described by Linnaeus as P. Polytes, 

 and was considered to be a distinct species till Wes- 

 termann bred the two from the same larvae (see 

 Boisduval, " Species General des Lepidopteres," p. 272). 

 They were therefore classed as sexes of one species by 

 Mr. Edward Doubleday, in his " Genera of Diurnal 

 Lepidoptera," in 1846. Later, female specimens were 

 received from India closely resembling the male in- 

 sect, and this was held to overthrow the authority of 

 M. Westermann's observation, and to re-establish P. 

 Polytes as a distinct species ; and as such it accord- 

 ingly appears in the British Museum List of Papilio- 

 nidae in 1856, and in the Catalogue of the East India 

 Museum in 1857. This discrepancy is explained by the 

 fact of P. Pammon having two females, one closely re- 

 sembling the male, while the other is totally different 

 from it. A long familiarity with this insect (which 



L 2 



