6 MR. A. R. WALLACE ON THE PAPILIONIDiE 



varieties are really cases oi polymorphism. Albinoism and melanism are of this character, 

 as well as most of those cases in which weU-marked varieties occur in company with the 

 parent species, but without any intermediate forms. Under these circumstances, if the 

 two forms breed separately, and are never reproduced from a common parent, they must 

 be considered as distinct species, contact without intermixture being a good test of 

 specific difference. On the other hand, intercrossing without producing an intermediate 

 race is a test of dimorphism. I consider, therefore, that under any circumstances the 

 term ' variety ' is wrongly applied to such cases. 



The Malayan Papilionidse 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. Papillo Ilemnon, L., is one of the most striking, as it exhibits the 

 raixtiu'e of simple variability, local and polymorphic forms, all hitherto classed under the 

 common title of varieties. The polymorphism is strikingly exhibited by the females, one 

 set of which resemble the males in form, vnih. 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 resemble P. Coon, a species of which the sexes are alike and inhaWting 

 tlie same countries, but with which they have no direct affinity. The tailless females 

 exhibit simple variability, scarcely two being foimd 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, AvhUe the continental speci- 

 mens, 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 — P. Androgens, Cr. 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 taiUess females, have all been bred fi'om a single 

 group of the larvae, by Messrs. Payen and Bocarm6, in Java, and I myself captured in 

 Sumatra a male P. Memnon, L., and a tailed female P. Achates, Cr., " in copula." 



Papilio Fammon, L., offers a somewhat simUar case. The female was described by 

 Linnaeus as P. Polytes, and was considered to be a distinct species till Westermann bred 

 the two from the same larva; (see Boisduval, ' Species G6nerales 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 insect, and this was held to overthrow the authority of 

 M. Westermaun's observation, and to reestablish P. Polytes as a distinct species ; and as 

 such it accordingly appears in the British Museum List of Papilionida; 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 resembling the male, while the other 

 is totally different from it. A long familiarity with this insect (which, replaced by local 

 forms or by closely allied species, occurs in every island of the Archipelago) has con- 

 A-inced me of the correctness of this statement ; for in eveiy place where a male allied to 

 P. Pammon is found, a female resembling P. Polytes also occurs, and sometimes, though 

 less frequently than on the continent, another female closely resembling the male ; while 



