THE YOUNG 



NATURALIST. 



63 



select a series of specimens in which this 

 band may be found in every imaginable 

 stage, from a clear well-defined bar to the 

 mere trace of an outline, or slight costal 

 blotch. We will find also that some species 

 are so variable in this particular that they 

 produce numberless transition forms, and 

 by an examination of these we may learn in 

 what manner change is made, if we are 

 unable as yet to say either why or how it 

 has been brought about. The British species 

 of the genus Melanippe and the closely 

 allied Melanthia present a very distinct 

 series of transitions. Melanthia ocellata has 

 the band unusually well defined, perhaps 

 as clearly as any other British species, but 

 Melanippe unangulata, tristata, rivata, biviviata, 

 and galiata all have it very well marked. 

 In montanata it is generally very distinct, 

 but it shows a tendency to break in the 

 middle, and in specimens from Shetland is 

 often quite broken. In fluctuata the costal 

 half only is well defined, the inner portion 

 being generally only slightly darker than 

 the ground colour, but this part is occasion- 

 ally wanting, and I have two specimens 

 where even the costal portion is reduced 

 to very small dimensions. Hastata has an 

 irregular black band, broken in the middle, 

 but I have one specimen where the two 

 portions are connected by a black line, and 

 two others where they are connected by a 

 double line ; in one of them the two lines 

 being nearly united, in which case it would 

 form a well denned band. Rubiginata has 

 generally the costal portion of the band only, 

 but there are frequently traces of the 

 remainder, two dark spots on the costa 

 often occurring. In my series of this 

 species I have one with a rather broad, well 

 defined and unbroken band ; another with 

 the band divided only by one pale wing 

 vein ; a third with two pale wing veins, 

 breaking it into three portions, and showing 

 how the two spots on the inner margin are 

 formed ; — these last two, to the unaided 



vision, appear to have an equally distinct 

 band to the first. Pr ocellata has also the 

 central portion of the band only, but the 

 remainder may always be traced in outline, 

 which is sometimes very distinct on the 

 inner margin. Lastly we come to albicillata 

 in which every trace of the central band 

 has disappeared, unless the faint spot at the 

 disc be considered part of it. From these 

 illustrations we see that the elimination of 

 the band is brought about in two ways. 

 First the band breaks in the middle, 

 the lower portion divides again at the 

 nervure, and gradually both parts disappear, 

 while the upper portion disappears rather 

 more slowly. In rubiginata alone the entire 

 process may be traced, as in the examples 

 named above. Hastata is equally illustrative. 

 Mr. Gregson has sent me a sketch of one 

 with a well defined band, my own connective 

 specimens are named above, while examples 

 where it is reduced to a few unconnected 

 spots are not at all rare. The Shetland 

 form of montanata is the next in order, and 

 those who have not specimens should 

 understand that those with a broken band 

 were not so common even there, as with it 

 united, but showing a tendency to break. 

 Tristata shows also a strong tendency to 

 break, I have one example where it is 

 quite broken in the centre, and Mr. 

 Gregson has one where the second division 

 is shown. Biriviata has not so strong a 

 tendency to break, but I have one small 

 specimen where it is distinctly divided. 

 Unangulata has usually a rather broad band, 

 but one of my series has the band narrow, 

 and much indented where the break would 

 first occur. Every form of change may thus 

 be found even in a limited number of 

 specimens. The second manner in which 

 the elimination of the band is brought 

 about may also be traced in these two 

 genera. While the outline continues 

 entire, the inner half of the band becomes 

 paler in colour, gradually assimilating 



