( Ixxxv ) 



of both sexes ; the wet-season specimens were highly remark- 

 able, being, especially in the females, nearly black. 



(b) Acrsea chseribula, Oberth., taken in the height of the dry 

 season ; remarking that : — 



" Dr. Butler * has suggested that checribida with its heavy 

 black apex may be the wet-season form of acrita. The speci- 

 mens shown seemed to demonstrate fairly certainly that this 

 is not the case. At the same time, an examination of the 

 series in the British Museum left it doubtful whether the 

 specimens there recorded by him under that name are the 

 true chseribula of Oberthiir. They appear to be only varia- 

 tions of acrita which, apart from its seasonal phases, is 

 undoubtedly a highly variable species." 



(c) Acrasa natalica, Boisd. — Dry and wet phases of both sexes ; 

 the dry specimens being characterized by their smaller size 

 and slightly brighter colour. 



Dry and wet phases of both 

 sexes, all exhibiting a tendency, 

 especially the females, to a 

 darker colour in the wet season. 

 Commenting on these species Mr. Neave said that he had 

 found the above change of colour in the seasonal phases, 

 which is common to all the above species, but is most marked 

 in acrita, exceedingly difficult to account for. The very 

 strongly aposematic coloration of this species in the dry 

 season when the struggle for existence is keenest is most 

 notable. It was, he thought, at this time of year, the most 

 brilliant insect on the wing that he knew. The change of 

 colour is also accompanied to some extent by change of habit, 

 dry-season specimens being much more restless and hard to 

 capture than wet ones. It seemed therefore difficult to 

 account for these facts without supposing that the brilliant 

 dry-season phases have been evolved, by stress of circumstance 

 at that time of year, from a duller coloured phase such as, in 

 this region, we still find in the wet season when the struggle 

 is not so keen. 



Seasonal forms in the Pierinse were represented by : — 



(e) A long series of Teracohis regina, Trim., of both sexes and 



* P. Z. S. 1894, p. 566. 



{d) Acrxa induna, Trim. 

 A. doidjledayi oncsea, Hopff. 

 A. caldarena, Hew. 



