Extracted from the Proceedings of the Entomological 

 Society of London of October Uh, 1898. 



Prof. E. B. PouLTON exhibited a series of Precis octavia, 

 (Cram.) var. natalensis Staud., and Precis sesamus, Trim., 

 both captured and bred by Mr. G. A. K. Marshall at 

 Salisbury, Mashunaland (5000 ft.) and read the following 

 notes thereon : — 



"The specimens exhibited prove conclusively (as Mr. 

 Marshall has shown in the July number of ' The Annals and 

 Magazine of Natural History,' p. 30) that these two butter- 

 flies, which differ so entirely in appearance and even in shape, 

 size and habits, are seasonal forms of a single species. Mr. 

 Marshall deserves the thanks of all naturalists for this dis- 

 covery of the most wonderful example of seasonal dimorphism 

 as yet known, and for the generous manner in which he has 

 despatched to this country the invaluable material constitut- 

 ing his evidence, so as to make it accessible for all time 

 in the British Museum and Hope Collection. 



'' Entomology is deeply indebted to Mr. Marshall for his 

 liberality now and at other times in placing large quantities 

 of valuable material at the disposal of investigators, and for 

 his readiness in undertaking biological observations ; and I 

 desire specially to thank him for constant help, and for 

 the valuable information contained in his letters, some of 

 which I hope to lay before the Society. 



" The relationship between Precis octavia-natalensis and 

 P. sesamus has been described by Mr. Trimen (S. Afr. Butt., 

 i, and iii, app.), who connected the two foi-ms by a number of 

 comparatively rare intermediate varieties, which, having 

 regard to the fact that the forms themselves had been captured 

 in coitu, he regarded as probably hybrids. The conclusion 

 that the two forms were examples of seasonal dimorphism 

 was reached by Mr, C. N. Barker and independently by Mr. 

 Marshall (Trans. Ent. Soc. Lond., 1896, p. 557). 



" Of this conclusion the specimens exhibited furnish 

 absolute proof. They include in the first place specimens 

 captured by Mr. Marshall towards the end of the wet (summer) 

 and beginning of the dry (winter) seasons. 



