6 MR. A. R. WALLACE ON THE PAPILIONIDÆ 
varieties are really cases of polymorphism. Albinoism and melanism are of this character, 
as well as most of those cases in which well-marked varieties oceur 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 cireumstances the 
term ‘variety’ is wrongly applied to such cases. 
The Malayan Papilionidæ 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, L., is one of the most striking, as it exhibits the 
mixture of simple variability, local and polymorphie forms, all hitherto elassed under the 
common title of varieties. The polymorphism is strikingly exhibited by the females, 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 resemble P. Coon, a species of which the sexes are 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 
surfaee, and may therefore be distinguished as a local form, while 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. Androgeus, 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 tailless females, have all been bred from a single 
group of the larvæ, by Messrs. Payen and Bocarmé, in Java, and I myself captured in 
Sumatra a male P. Memnon, L., and a tailed female P. Achates, Cr., “in copulä.” 
Papilio Pammon, L., offers a somewhat similar case. The female was described by 
Linnzeus as P. Polytes, and was considered to be a distinct species till Westermann bred 
the two from the same larvæ (see Boisduval, * Species Générales des L£pidopteres,’ 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. Westermann's observation, and to reestablish P. Polytes as a distinct species; and as 
such it accordingly appears in the British Museum List of Papilionidæ in 1856, and in 
Hm Catalogue of the East India Museum in 1857. "This discrepancy is explained by the 
faet 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- 
bom me of the correctness of this statement ; for in every place where a male allied to 
. 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 
