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sundry transverse lines ; all apparently agreeing as to the " much 

 dusted with black " character. Such a description well covers the 

 forms usually met with, and applies equally well to a portion of 

 the Eastbourne individuals ; but in a much larger proportion 

 of them the "black dusting" is so nearly absent as to give the 

 insect the appearance of having a clear bone-coloured ground, 

 with sundry transverse grey lines, what few black scales there are 

 being confined to the basal portion of the wing within the first line, 

 and are often visible only when viewed through a fairly powerful 

 lens. I at first thought the absence of dusting might be the result 

 of age, but I have taken this form fresh from the pupa, with wings 

 still hanging limp, and yet with hardly a black speck on them. For 

 some years the only specimens met with that showed any variation 

 that did not come well within the two extremes above mentioned, 

 /. e. the usual grey-looking dusted, and the bone-coloured plain 

 forms, were two taken in 1889, which, although the outer three- 

 fourths of their wings are almost devoid of any " dusting," have the 

 black scales so thickly placed on a portion of the basal fourth as to 

 give them the appearance of having blackish basal patches. But 

 during the present summer I had the good fortune to find three 

 examples so densely covered with the black dusting as to give the 

 appearance of a black insect with pale submarginal line, analogous 

 to the so-called black forms of several of the species of the genera 

 Boarmia and Tephrosia. 



No doubt the natural resting-place of the insect was originally the 

 chalk cliff, but under its present artificial conditions it rests with 

 outstretched wings on the rough walls that keep up the earth-banks 

 along the parades. These walls are constructed of a sort of sand- 

 stone peculiar to this part of the coast ; it is somewhat variable in 

 tint, but comes within the various shades of grey, and the ordinary 

 forms of the insect harmonise with it so well that sometimes when 

 boxing a specimen, if the species is fairly abundant, one sees one, 

 two, or even three or four others resting close by that had escaped 

 previous notice. Not so, however, with these "black" forms, which 

 appeared as conspicuous objects even at some little distance. One 

 is consequently somewhat at a loss to understand what useful purpose 

 in the insect's economy is served by the assumption of this dark form. 



The species, judging by the literature of the subject, appears to 

 have been generally regarded as single-brooded, its time of appear- 

 ance being variously stated as June and July by some authors, and 

 July and August by others. This arises, I think, from a confusion 

 of two broods. Some years ago, when at Shanklin, Isle of Wight, I 

 found the species very commonly on the street lamps in the first 

 week of July, but all that were then taken were much worn, 

 evidently the late stragglers of a June brood. Unfortunately my 

 visits to Eastbourne have been confined to the months of August 

 and September, but they have extended over a sufficiently long 

 period of those months to enable me to note the earliest emergences 



