402 Mr. G. A. K. Marshall on 



2 $), and four oi E.wahlhergi (3 ^, 1 $), which he had cap- 

 tured on the Umbilo River, near Durban, Natal, on June 

 28, 1897. His account of the habits of this little com- 

 pany is given below. 



" Maheroi, Natal; Od. 7, 1897.— The specimens of 

 Eitralia mima and wahlbcrgi were captured going to roost 

 together on a small clump of ferns under a steep kraantz 

 between 3 and 4 p.m. Although disturbed a good many 

 times in my efforts to catch them, they always returned 

 after some minutes. There were two others which were 

 too tattered to keep, and two more tbat I failed to catch." 



If Mr. Marshall's conclusion be established, it follows 

 that the corresponding and closely-allied mimetic West 

 African forms JtJiiralia anthrdon and E. (IvMa, connected 

 like ivahllin-gi and niivia by intermediate varieties, are 

 similarly the dimorphic forms of a single species. 



H. Groups of Synaposcmatic Acr.vas captured at the same 

 Place a7ul Time. 



Professor Meldola first suggested the use of Fritz 

 Mliller's principle to explain " the prevalence of one type 

 of marking and colouring throughout immense numbers 

 of species in protected groups, such as the tawny species 

 of Danais, the barred Hclironias, the blue-black Euphvas, 

 and the fulvous Acnras" (Ann. and Mag. Nat. Hist., 

 ser. 5, vol. x, 1882, p. 425). As an example of Mullerian 

 mimicry in the last-named group, I was anxious to obtain 

 convergent species captured in one place and at one time. 

 Mr. Marshall very kindly obtained two such groups for 

 me. The first was captured by him on Dec. 31, 1898, 

 at Salisbury, and contains the following species : — 



G Acr.va douhlcdayi, var. aodna, 4^2$ (^ Fig, 1, $ 



Fig. 2, Plate XVJ). 

 4 Arr/va caldarena, 3 ^ 1 $ ((^ Fig. 3, $ Fiij. 4, Plate 



XVl). 

 4 Acr.va nohara, var. ludali, 2 ^ 2 $ (^^ Fig. -5, $ 



Fig. 0, Plate XVI). 

 2 Acr/ea violarum, var. ascraa, 2 $ (Fig. 9, Plate 



XVI). 

 2 Acr/va raliira, 1 ^ 1 $ (^ Fig. 7, $ Fig. 8, Plate 



XVI). 



All these species are of approximately the same size 

 and shape of wing, colour, and pattern, raAtVa being furthest 



