362 L. de Niceville & Dr. L. Martin— Butterflies of Sumatra. [No. 3, 



As mentioned above, north-eastern Sumatra does not possess a 

 well-marked dry- and wet-season, such as is found over most of the 

 continent of India, there being no month in the year when it does not 

 rain ; indeed it is rare for a week to pass without a shower, consequently 

 there are no dry-season forms of butterflies to be found in Sumatra except 

 the dry-season form of Melanitis ismene, Cramer ( = ZecZa, Linnaeus, aucto- 

 rum), which, as also in Java, is found all the year round equally commonly 

 with the wet-season ocellated form, M. determinata, Butler. 



We would especially bring to notice the occurrence in North- 

 Eastern Sumatra of a very peculiar endemic form of the female of Papilio 

 miemnon, Linnaeus. It belongs to the first form group of females of 

 the species, i.e., the form which has no tail to the hindwing and is 

 most like the male ; the second form is also tailless, but has a large 

 white patch on the outer half of the hindwing never found in the 

 first form. This peculiar first form female has the " epaulettes " (i.e., 

 the basal portion of the discoidal cell of the forewing on both surfaces) 

 almost pure white, faintly tinged only with ochreous, so that it may 

 perhaps be called cream-coloured. It probably mimics the second form 

 female of Papilio forbesi, Grose Smith, which also possesses similar 

 white epaulettes, the first form lacking them altogether, and is 

 therefore like the male. It may be urged against this theory that 

 females of P. forbesi are very rare, especially the white-epauletted 

 second form, Dr. Martin having obtained only two specimens of it. 

 But this scarcity is probably more apparent than real, both sexes of 

 P. forbesi occurring in equal numbers, but the males coming down to 

 the hill streams to drink are caught in large numbers, while their less 

 thirsty spouses keep only to the thick forest where they escape the 

 danger's of the butterfly net. 



It should be pointed out that de Niceville is solely responsible for 

 the nomenclature employed in this paper, and for all statements ap- 

 pearing in the first person singular, together with the descriptions of 

 species and sexes ; while Martin, who has lived for 13 years in north- 

 east Sumatra, is mainly responsible for the notes on distribution in the 

 island itself, scarcity or rarity, season of occurrence, &c, of the 

 various species ; de Niceville having but twice visited Sumatra, and 

 then only for short periods. 



The literature of the subject is of course very scattered and frag- 

 mentary. The following is a list of the principal papers dealing with 

 the Rhopalocera of Sumatra : — 



I. P. C. T. Snellen. Tijd. voor Ent., vol. xx, p. 65 (1877), " Le- 

 pidoptera op Sumatra verzameld, voornamelijk in Atchin." Enumer- 

 ates 35 species. 



