1910.] FROM NORTHERN RHODESIA. 19 



is evidently its nearest ally, but it differs in several particulars. 

 Besides being a notably smaller insect, it is characterised by the 

 presence of two subapical spots in primary which never occur in 

 acriia and by a different arrangement of the submarginal spots 

 in areas 3, 4, 5, 6 of secondary. A. lualabce also differs in colora- 

 tion and shape of the abdomen. 



ACR^EA CHJERIBULA. 



Acrcea chceribula Oberth. Et. d'Ent. xvii. p. 19, pi. ii. fig. 16. 



Acrcea acrita var. chceribula Auriv. Rhop. Afr. p. 96. 



I found this species plentiful throughout the high plateau 

 country of Northern Rhodesia and Katanga, especially in the web 

 season, though it occurs throughout the year. It frequents wood- 

 land, particularly wooded hills, and is rather active on the wing, 

 but easily captured as it flies very low and is by no means shy. 



This insect has been confused by some authorities with acrita 

 Hew., but is unquestionably distinct. I have no doubt on this 

 point, having taken some 200 individuals at all seasons and having 

 an even larger series of acrita with which to compare it. It may be 

 distinguished externally by its uniformly smaller size, very deep 

 black apex which is constant at all seasons, and black basal patch 

 on uppermost part of base of secondaries. It differs also in colour, 

 being, especially in the bright dry-season specimens, of a clear 

 orange-red, never the rosy scarlet of acrita. The spots on pri- 

 maries are further never enlarged in the wet-season as in acrita. 

 Finally, the male genitalia differ considerably from those of acrita. 



Aor^ia periphanes Oberth. 



This species is exceedingly abundant in plateau country every- 

 where west of the Mchinga escarpment. It does not apparently 

 occur in the Luangwa valley. A very long series of this species 

 of some 250 specimens exhibits very clearly what an astonishingly 

 variable one it is. It appears to be in a highly unstable condition 

 and' to be in process of forming two or more well marked varieties. 

 The chief of these are : (1) resembling the type figured by Oberthur 

 Et. d'Ent. xvii. p. 20, pi. ii. fig. 23 ; (2) a form in which the whole 

 outer margin of the secondaries is suffused with black on both 

 surfaces. On the underside the rectangular outer marginal spots 

 of the type form are more or less overwhelmed and remain only 

 as small triangular patches in the black ground. 



The fringe in this form is also blackish, instead of whitish as 

 in the type form. This character of a heavy black hind margin 

 is usually, though not necessarily, associated with a rose-coloured 

 suffusion of, at least, the secondaries. It is possible that this form 

 exhibits a mimetic approach to the above mentioned A. ivehvitschi 

 Rogerh., which is so conspicuous for its bright cerise colour and 

 heavy black margins. I had for some time considered this form 

 to be a seasonal one, but this appears to be not so. Though the 

 latter is perhaps a trifle the commoner in the dry season, both 

 forms occur in nearly equal numbers throughout the year. 



2* 



