( xxxix ) 



upper (notwithstanding the one distinguishing feature described 

 above), comorarum is far nearer to saclava than is frohenia or 

 even dumetormii. In the north-western species the markings 

 on the under surface are paler than those of the upper, while 

 the minute markings are lighter than the larger. The under 

 side of dumetorum is remarkable in the fact that the chief 

 spot of the fore-wing is fulvous while the other markings and 

 those of the hind-wing are white. Indications of the same 

 contrast exist, although far less developed, in frohenia. 



These are the chief characteristics of colour and pattern 

 which distinguish the four island species from one other and 

 from the Madagascar saclava. It is of great interest to attempt 

 the difficult task of reconstructing some stages of the past 

 history of the group. We may confidently assume, from the 

 greater affinity to saclava on the innermost island on each 

 side, that all the four forms were derived from Madagascar ; 

 and, if amount of change be a measure of period of isola- 

 tion, that frohenia was first isolated, dninefornm second, 

 comorarum third, and mayottensis fourth. "We must if possible 

 distinguish in each case between ancestral characters which 

 have persisted from a period previous to the isolation, and 

 recent characters which have been evolved since its beginning. 

 The former are of special interest in that they suggest to. us 

 some of the features which saclava has now lost in Madagascar. 



a. Ancestral Features. — 1. Tlie Band Crossing the Hind- 

 Wing. — Saclava in Madagascar has a considerably broader 

 band than on the mainland of Africa. It is probable that 

 the Madagascar saclava also formerly possessed a narrower 

 band, which still persists in three out of the four island forms. 

 It is probable that the band of saclava has been widened in 

 consequence of synaposematic approach to the other species of 

 N'ejJtis in Madagascar, and perhaps partially under the influ- 

 ence of Amauris nossivia, Ward, in Avhich the white markings 

 are so strongly developed. The synaposematic sensitiveness of 

 jVeptis to the African species of Amauris as well as to other 

 Danainx in other regions has been referred to in Trans, Ent. 

 Soc. Lond. 1902, pp. 467-8, Ne2)tis kikideli, Boisd., of Mada- 

 gascar, described as a common species by Mabille, is distin- 

 guished by a great development of the white markings, and 



