( 37 ) 



becomes the pale yellowish and black sub-species arenaria, 

 E. M. Sharpe, at Entebbe. 



"When we pass from the western to the eastern side of the 

 geogi'aphical range, Plamena epaea becomes a duller, darker- 

 looking butterfly ; Planema consanguinea, on the contrary, a 

 far lighter and paler butterfly. If, neglecting the immense 

 difference in general appearance, attention be fixed on the 

 fact that the fulvous pigment of the male epaea and both sexes 

 of consanguinea becomes pale yellow in the east, we are met 

 by the fact that the male Planema alcinoe, Feld., from Lagos, 

 preserves the very same fulvous tint unchanged at Entebbe, as 

 do the male montana, Butl., form of P. aganice, Hew., the male 

 P. macarista, E. M. Sharpe, and both sexes of P. poggei 



[xci 

 nelsoni, Grose-Smith. Further evidence against the hypo- 

 thesis of climatic influence was derived from Mr. Wiggins's 

 series of P. paragea, in which were found the two remarkable 

 specimens exhibited to the meeting. In one of these, a male 

 captured June 26th, 1910, the yellow markings had almost 

 entirely disappeared, while in the other, a female, taken Aug. 

 29, 1909, they were immensely extended, especially on the 

 hind-wing, where the pale expanse was even two or three 

 times as large as the white area of the female epaea from 

 Lagos. Here was a single individual in which the normal 

 change in the eastern part of the range was reversed, the 

 insect being lighter and paler instead of dingier in appeai'ance. 

 Such a variety throws sti'ong light upon the origin of mimetic 

 resemblance ; for this pale individual presents considerable 

 likeness to P. arenaria, and affords the foundation upon 

 which a close resemblance might be developed by selection. 

 There can hardly be any example as yet known which better 

 enables us to understand the production of mimicry between 

 forms closely allied but superficially very different in appear- 

 ance : yet in its production the operation of climatic influence 

 is extremely improbable, and we are thrown back upon causes 

 of variation at present unknown and mysterious. 



PSBUDACRAEAS OF THE HOBLEYI GROUP ON DaMBA ISLAND AS 

 COMPARED WITH THOSE FROM THE ENTEBBE DISTRICT. Prof. 



Poulton exhibited a set of the mimetic Pseudacraeas and their 



