ON THE CORRELATION OF PATTERN IN RHOPALOCERA. 181 



observed, but the clasps are very different, there being a considerable 

 change of shape in them, whilst the super-structure comes nearer 

 to our common British pldaeaa than to the general form. I have 

 mentioned these three species of one genus so as to show- 

 specific variation of armature with also small variation of colour. 

 We will now take three species of marked difference in colour into 

 consideration. Ruralis betiilae with an entirely' brown male and an 

 orange spotted female, R. In tea, which is entirely orange in both sexes, 

 the underside of these two being very closely alike, and a brilliant 

 metallic green species Ruralis on'oitalis wdth a different underside closely 

 allied to Ruralis (jnercua, already referred to (see antea p. 179). R. betulae 

 (PI. xviii., fig. 20), has a very large hooded tegumen, not excised on 

 the dorsum at all, with large strong falces attached to its lower front 

 extremities ; the girdle is broad, strong, erect, deeply excised at rear ; 

 the aedffiagus is small, rather short, straight, somewhat tapering,, 

 whilst the clasps are very small and broadly oval with no processes. 

 This is the type of the genus. In R. lutea (PI. xviii., fig. 20A), the 

 tegumen remains the typical, unexcised, hooded-shape, but it is much 

 smaller in its dimensions, the falces being also much smaller ; the 

 redoeagus is very large and similar in general shape and size to 

 quercus, the girdle and the clasps also are more nearly allied to 

 quercus than to betulae, the clasps having a protruded lobe-like process 

 at their upper apex. In R. orientalis (PI. xviii., fig. 22), with its 

 underside pattern so closely allied to quercim, we find the armature 

 rather nearer to betulae than to quercus. The hooded tegumen is more 

 ample, the tedoeagus is quite close in shape to the small aedoeagus of 

 betulae, whilst the clasps, though larger than betulae, are nearer to that 

 species than to quercus. The variation of species inter se has thus been 

 demonstrated, but it will also be advisable to examine two other cases 

 of specific inter se variation, in cases where species are very different 

 superficially, but where their armature is so close that only a very 

 expert eye would observe anything to raise a doubt in hismmd — 

 and cases where the imagines are exceedingly close superficially, but 

 the male armature is less so. Professor Poulton has drawn my 

 attention to this, and has enabled me to show this little group of 

 African species of the genus Acraea. These species do not affect my 

 main argument, but they are most interesting in shownig that specific 

 variation occurs* also in the genus Acraea, as one would expect, though 

 it seems to proceed on different lines to what occurs in the Ruralidae, 

 In Acraea zetes and A. cliilo we have two species that appear very 

 different superficially, the former with its entirely blackish primaries 

 and heavily marked secondaries, the latter pinkish tawny in both 

 wings. If, however, we examine the spots of the wings we find they 

 are very close indeed. Eltringham in his able monograph places them 

 next each other and we find the armature is so close that it needs a 

 critical examination to discover the differences that, as a matter of 

 fact, do exist. The two species are as nearly the same size as can be,, 

 but the armature of zetes (PI. xviii., fig. 23), is decidedly smaller 

 than that of cltilo (PI. xviii., fig. 24), the uncus and tegumen are 



* By specific variation I mean vaiiation between species hiter $e of the same 

 genus— not that the same species has differentiation in armatnre, this I have not 

 found. 



