1921] MouLTON : Malaysian Butterflies. 175 



Distrib. India to China and the Malay Peninsula, with 

 subspecies scattered through the Malay Archipelago to 

 Australia. Those recognized from Malaysia are ■ — 



D. p. plexippus Linn. Malay Peninsula 



D. p. sumatrana Moore Sumatra. '- ^ 



D. p. niasiciis Fruhst. Nias I. 



D. p. intensa Moore Borneo, Java, Bali, Bawean. 



The forms with white, instead of fulvous, ground- 

 colour in the hind wing should be known as form inter- 

 media Moore. They occur together with the typical fulvous 

 hind-winged form in Tonkin, Saigon, Siara and the Malay 

 Peninsula, and therefore cannot be regarded as a separate 

 subspecies. Distant ^ recognized this in 1886, but 

 Fruhslorfer ^ records intermedia as a " geographical rac ' " 

 confined to the Malay Peninsula and Singapore (where he 

 states it is the principal form) and as an " aberration " 

 occurring in the dry season in Siam, Saigon and Tonkin. 



It seems to me preferable to reserve subspecific names 

 for geographical races inhabiting separate areas. In this 

 case two well-marked forms occur together over a wide 

 range of country. To recognize them by form names 

 rather than as distinct subspecies appears to me the sounder 

 policy. If one were a resident form and the other a visitor, 

 as occurs in some species of birds, {e.g. the Eastern Roller, 

 Eurijstomus orientalis Linn., which has the typical form 

 orienlalis resident in Malaysia, and a migi*atory subspecies 

 calonijx, which is also found at certain times of the year in 

 Malaysia together witli orientali.s), subspecific distinction 

 would be justified. There is, however, no evidence to sho\i' 

 that either form of plea'ippus is an occasional visitor to our 

 subregion. It is to be supposed in fad that tbe two forms 

 will occur in one brood. A breeding experiment to test 

 this would be of interest. On the other hand it might be 

 argued with some justice that individuals which produce 

 dimorphic broods in one area are subspecifically distinct 

 from individuals in another area where only one pattern 

 of progeny is produced, not two. 



One male in the F.M.S. Museums from Kuala Kangsar 

 has a very slight development of white in the discal region 

 of the hind M'ing above and is thus intermediate between 

 the typical forni with completely fulvous hind wing and 

 the white hind winged form intermedia. This form may 

 be termed connectens f . nov. 



23. Danaida plexippus Linn, intensa Moore. 



Danaida plexippus inlensa Frulistorfer 1910, p. 195. 



The distribution of this subspecies, viz. Borneo, Java, 

 Bali and Bawean, is rather curious. 



' Distant, 1886, p. 408. 



' Fruhstorfer, 1910, p. 185. 



