64 



THE YOUNG NATURALIST. 



more and more with the ground colour, 

 then the outline becomes less distinctly 

 defined, breaks into dots, and eventually all 

 trace of it is lost. Fluctuate is the most 

 marked illustration of this change, in these 

 two genera. I do not know of a specimen 

 with the band equal across the wing, but the 

 inner portion is nearly always distinct, 

 though paler than the costal half, and the 

 outline is nearly always well defined. Two 

 varieties of it in my collection are mentioned 

 above, one of them has the costal blotch 

 very small, but well defined, and the 

 inner portion much narrower than usual. 

 The other has the costal mark still 

 smaller, and no trace whatever of the lower 

 portion. The first of these is very abnormal, 

 for the undulating lines are wanting, and in, 

 colour it is rather of a pale yellowish brown. 

 Procellata comes next to this, and I know of 

 no example where more than the outlines of 

 the band can be traced on the lower portion 

 of the wing. Albicillata showing no trace of 

 the central band may have had it eliminated 

 by either process, or by both, for both 

 processes appear to be operating with 

 montanata. 



The genera Cidaria might have been 

 selected in lieu of the foregoing for illustra- 

 tion of the manner in which the band 

 becomes lost, but the marked divergency of 

 of colour among the Cidaria makes the 

 species look so different that they appear to 

 be more diversified than those already 

 examined. Leaving out the question of 

 colour, the genus may be examined from 

 the same standpoint, which I will do as 

 briefly as possible. Psillicata, miata, 

 sagittata, suffunuda, prunata and fulvata 

 all have the band distinctly defined right 

 across the wing. Silaceata has a distinct 

 enough band, but it is nearly always divided 

 by pale lines like the rubiginata named 

 above. It has in fact a band of three 

 distinct portions, the central one being the 

 smallest. Specimens however are not 



uncommon with the band entire, and I have 

 one with it very broad and distinct. Cory- 

 lata has the same peculiarity more decidedly 

 marked than in silaceata, but the band is 

 only in two portions. Though this 

 characteristic is so striking that the species 

 is called the Broken Bar Carpet, examples 

 are not rare in which it is unbroken. 

 Testata, pojndata, pyraliata, anddotata have 

 the outlines of the band easily traceable 

 across the wing ; most distinctly at the 

 costa, where it is often darker between the 

 lines. Of all these species, examples may 

 be found in which it is well marked across 

 the wing, but that is not the ordinary form, 

 and the gradations from one to the other 

 are commoner than the extremes. Russata 

 and immanata are so exceedingly variable 

 that it is difficult to speak with any 

 certainty of their tendencies. The band is 

 more frequently well defined in immanata, 

 and seems to tend to become paler 

 in the central portion, and to break 

 towards the inner margin. Russata is 



! often pale or reddish at the central 

 portion of the wing, and in some examples 

 it is difficult to trace the band at all. A 

 longer series of these two species than I 

 possess, might help to an understanding of 

 the changes, but leaving these two, all the 

 others might be classed with those of the 

 genera already discussed. 



If space permitted, other changes of the 

 band, in shape, position, &c, and its per- 



I feet elimination might be traced without 

 going further than our British species for 

 illustration. This, however, would be 

 wearisome, and does not seem necessary to 

 lead us to the conclusion at which I desire 

 to arrive, — That the band in this group of 

 Lepidoptera is derived from a common 

 ancestor, and is gradually being eliminated 

 from the wings of many species. Why it 

 remains so very distinct on some insects, 

 oeellata for instance, is quite another matter. 

 Nor can it be admitted that a reverse action 



