182 



THE ENTOMOLOGIST S RECORD. 



slightly different in shape, the girdle of zetes is more erect and 

 decidedly slighter, the pilosity of the clasps is markedly diverse 

 from that of chilo, being much longer, thicker and heavier,, whilst 

 the fedoeagus of chiln is longer and ditt'erent in sha.pe in the basal 

 area. The saccus also is quite different in the two insects. The 

 species look very different, they are, however, very closely allied, 

 and the armature follows their specific relationship, not their super- 

 ficial facies. This is as we should expect. Agajn there are two forms 

 A. natalica var. p^t'udci/ina (PL xix., fig. 25), and A. natalica (PI. xix., 

 iig. 26), as also A. acn'ta var. amhii/ita (PI. xix., fig. 27), and A. 

 Mcrita var. jiudarina (PI. xix., fig. 28). Both these two pairs are 

 .decidedly different, but we have in each case natalica and its various 

 , races, and acrita with its various races, so that in the light of Mr. 

 Eltringham's monograph, we might quite properly call them two 

 polymorphic species, with wet and dry forms and intergrades almost 

 all along the line. In these cases we should not expect their structure, 

 such as neuration or armature to change, and so it is, the structure 

 remains true though the colour differs. It is a case of that unknown 

 quantity x in the constitution of the species (would that we could find 

 out what .*■ is) that under different conditions causes the mutability of 

 species, the most interesting factor of it being why some species respond 

 and why others do not. 



This brings us to the second and last instances I have to draw 

 attention to, viz., similarity of design but difference in structure. In 

 Aciaea peri/ihanes var. acritoides (PI. xix., fig. 29), and A. acrita (PI. 

 xix., fig. 30) we certainly have a superficial, a very superficial, resem- 

 blance, but the armature is very different. At the same time I must 

 say that no experienced entomologist would hesitate in at once separ- 

 ating the two species ; some of the spots in the secondaries assume 

 quite different positions. With Acraea calderena (PI. xx., fig. 31), and 

 A. piidorella (PI. xx., fig. 32), the case is more interesting; they had 

 always been considered forms of one species so exceedingly close were 

 they, and I think it was due to Mr. Eltringham (I speak under correc- 

 tion) that they were discovered to be distinct species, his armature 

 . dissections proving this. At the same time the postmedian line of 

 spots is quite different in the two insects, and it was this, no doubt, 

 that induced the query in Mr. Eltringham's mind. In A. chanibed 

 and A. mansya the difference in the perfect insects, the absence of 

 many spots on the upperside in the latter, would at once lead one to 

 expect the divergence of armature that we see (PI. x}s., figs. 38, 34). 



Finally I would refer to the genus Aviauris, to the two species A. 

 er/iena Ya,v. jachoni (PI. xx., fig. SI) dnd A. alhimaciila var. hanninrjtoni 

 (Pi. XX., fig. 38), and also to the species A. danfeldti and a new species 

 from Angola that I call A. an(/olae. The first two are separable only 

 , by the size and shape of the sexual brand on the secondaries and by 

 the palpus of the first being spotted, Avhilst the second is streaked. A. 

 .avijolae and A. danfeldti are separable in precisely the same way, but 

 their colour is white and black, instead of being more or less yellowish, 

 as in the other case. 



The male armature differs likewise (PI. xx., figs. 39, 40), the contour 



. of the clasps differs in each species, whilst the terminal sternite, which 



in this genus is furnished with very formidable teeth, differs in the 



: shape, in the size, and in the abundance of teeth. This last character 



