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F.R.S. These latter were of great value in working out the 

 species of this important group of mountain butterflies, upon 

 which Mr. Elwes is the recognized authority. 



An invaluable collection of 495 insects from Mashonaland, 

 nearly all from the neighbourhood of Salisbury, and 2 from 

 near Durban, Natal, were presented by Guy A. K. Marshall, 

 Esq. The General Collection has been enriched by an 

 important addition of specimens, in beautiful order, and with 

 more complete data than almost any others in our possession. 

 Furthermore a large number of specimens represent the 

 material which Mr. Marshall has specially collected, in 

 order to work out and illustrate various biological problems 

 of the utmost interest. 



Thirteen examples of Precis scsavms were in reality 

 presented in i(S98, and are briefly referred to in the Report 

 of that year. They were however inadvertently omitted from 

 the catalogue of Mr. Marshall's donations in 1898, and are 

 therefore included in those of 1899. These specimens are 

 historic, for they constitute the evidence of the most wonderful 

 known example of seasonal dimorphism, proving that the red 

 and black Precis octavia-natalensis is the summer form of the 

 blue, black, and red P. scsavms, a butterfly which flies in the 

 comparatively dry winter, and differs from the former in 

 habits, pattern, size, shape of wing, and in the relation of the 

 colouring of the under side to that of the upper side of the 

 wings. The series contains specimens of the former captured 

 at the end of summer, and of the latter at the beginning of 

 winter, 1898 (a fourteenth specimen, of ^^Az'Z^/^?, captured in 1899 

 carries the sequence on for another season), as well as two 

 female specimens of /'. octavia-natalensis, and butterflies of the 

 other form obtained from the eggs which they laid. A beautiful 

 photograph of the whole group, taken by Mr. Alfred Robinson 

 of the University Museum, is now at the Paris Exhibition. 



Mr. Marshall also presented many groups illustrating 

 Mimicry and Common Warning Colours among insects. 



A group of 18 specimens of 5 very similar species of Acraca, 

 captured on one day, illustrates the tendency of the insects of 

 specially protected groups to assume a similar appearance. 



