92 



THE YOUNG 



NATURALIST. 



It is quite unnecessary to take up space by 

 multiplicity of illustrations. Pale females 

 of nearly all the European species are known 

 to exist, aud most of them have distinctive 

 names. Pale females of many Exotic species 

 are also known, and it is probable that an 

 extended acquaintance with the others will 

 result in their discovery. Can we doubt 

 then, that we have in these pale varieties of 

 one sex, a case of reversion to a common 

 ancestor. We might possibly go even fur- 

 ther back than the ancestor of the genus, 

 and imagine a species with a yellow-winged 

 male and paler female and with red antennae, 

 from which both the genus Colias and Gon- 

 epteryx had sprung ; but to attempt this is 

 beyond the scope of the present enquiry. 



Among the many extraordinary varieties 

 in Mr. Gregson's well-known collection is 

 one of Anthocavis cardamines, taken at South- 

 port, that appears to me to present an 

 instance of reversion, and another specimen 

 or two in other collections still further 

 illustrate it. The female of this well-known 

 butterfly has all the wings white, with a 

 black disc spot, and a black patch at the 

 tip of the fore wings. The male differs by 

 having a smaller black patch at the tip ; but 

 with the outer half of the fore wings, from 

 the disc spot to the patch at the tip, deep 

 orange instead of white. No other species 

 of the genus occurs in Britain, but among 

 those found in Europe are three or four 

 with the wings yellow instead of white. 

 This I take to be the original form ; and 

 it is to this form Mr. Gregson's specimen 

 reverts, for it has the whole of the wings 

 saffron yellow, except the usual black marks 

 and the orange patch. In fact, it would 

 attract less attention if placed with a series 

 of A . eupheno or A . euphenoides than among 

 its own kind. Yet it is an unmistakeable 

 male cardamines. Mr. Bond has another 

 variety of this insect, a male, taken in 1873, 

 at Croft, in which the usual orange of the 

 tip is replaced by pale yellow. It is perhaps 



scarcely right to call this an instance of 

 reversion, as I am not aware that any 

 species exists with yellow tips, but I refer 

 to it as an illustration of the tendency of the 

 species to revert to yellow. Dr. Gill has a 

 still more abnormal specimen. Many fe- 

 males exist in collections with small patches 

 of orange on one or both sides. Dr. Gill's 

 specimen has a small orange patch near the 

 anal angle on both sides, shading off above 

 into yellow, thus displaying in a single 

 female the colours of both sexes, and also 

 the colour of the original form, if my con- 

 jecture be correct. 



It would be wearisome to multiply exam- 

 ples ; I have said enough to illustrate my 

 meaning. Where a variety assumes a pecu- 

 liarity common to its near allies, I consider 

 it to be a case of reversion. Where a num- 

 ber of closely-allied species have some 

 peculiarity in common, there can be no 

 doubt it has been derived from a common 

 ancestor ; and the larger the number of 

 individual species so allied, the greater the 

 certainty of their having all sprung from a 

 form possessing such characteristic, and 

 the less likely is it to have been assumed by 

 each separately. The subject is a very wide 

 one, and to trace every instance of reversion 

 to its source would require a much greater 

 knowledge of the subject than I possess. 

 What I have said, and the illustrations I 

 have given, will, I hope, enable beginners 

 to understand what is meant by the term ; 

 and as they become better acquainted with 

 the objects of their study, they will be able 

 to find other cases of reversion for them- 

 selves. 



REVIEW. 



"Check List" and "Label List" of 

 the Insects of the Dominion of Canada. 

 — These useful lists have been compiled by 

 the Natural History Society of Canada, with 

 the double purpose of registering " the 



