196 



OPORINIA. By L. B. Prout. 



angle generally not quite so sharp; discal dot in both sexes minute, sometimes almost obsolete. Hindwing 

 even more weakly marked than in dilutata. Much less variable than the other species ; even the sexual dimor- 

 phism is in some localities almost inappreciable, though more strongly marked ?? are also known. — ab. 

 ohlita. oblita Allen has the ground-colour somewhat more smoky, though less brownish smoky than in dilutata, while 

 nothing so extreme as dilutata ab. obscurata and ab. melana is yet known. This is the only form of the 

 latifasciaia. species as yet found round London. — ab. latifasciata ab. nov. is a striking form, precisely parallel to the 

 dilutata aberration of the same name, the basal and median areas of the forewing being entirely fuscous. The 

 whiter, more weakly lined ground-colour renders it still more beautiful than the corresponding form of dilutata. 

 Allen mentions it from Enniskillen and I have seen a long series which were collected with the type form 

 and some intermediates in N. Argyleshire. — The egg is closely similar to that of dilutata but appareatly even 

 more highly polished. The larvae are not yet conclusively differentiated, but the red or purple dorsal markings 

 of dilutata are in christyi often smoky blackish. It shows a preference for beech and elm, but has also been 

 found on birch, alder and sallow. It has not yet been taken wild on oak or hawthorn, which in some loca- 

 lities are the favourite food-plants of dilutata. The moth appears at about the same time as dilutata and is 

 local in woods in the British Islands, Central and N. Germany and Austria. Probably when it is better known 

 it will prove to have a considerably wider range. Hybrids of dilutata X christyi and christyi X dilutata are not 

 difficult to obtain in captivity, but are not known to occur in a state of nature. 



autumnata. 



approxt- 



maria. 



0, autumnata Bhh. (^ nebulata Thib. nee Scop., autumnaria Weaver, addendaria B. White, pallescens 

 Ckll., paUida Clark) (9 f). Antenna in cT slender, the joints not swollen anteriorly, cf genitalia with no hook 

 on the harpes. Wings strongly glossy, silvery white, silvery grey or in the darker forms purplish fuscous, 

 never with yellow or distinctly brown tone. Forewing with subbasal line ' distinctly marked, sharply angled 

 in the cell; antemedian line often followed by a strong fuscous bar, the median vein here almost invariably 

 blackened; postmedian line bent at a right angle between the P' and 2""* radials, then nuich straighter than 

 in dilutata. Hindwing in general appcarmg slightly longer than in dilutata, the distal margin being more 

 extremely convex; white, except in the darkest specimens; weakly marked, the lines less curved than the distal 

 margin. Extraordinarily variable. The name-type has the ground-colour silver white and the lines pale brown. 



sandbergi. — ab. sandbergi Lampa (= virgata Clark) dilfers in having th3 pale brown lines replaced by fuscous bars, 

 the ground-colour remainijig pale. Described from Sweden but occurs in various localities. According to 

 Derjugin it was very abundant in N. Lapland in 1908. — In ab. approximaria Weaver (^typica Clark) the 

 gromid-colour is darker (violet-grey), the markings moderately well expressed. It is generally as common as 

 the type. The original specimens were of a rather small race, transitional towards fHigrammaria and were 

 believed to have fed on pine. My Swiss series bred from larch belong almost entirely to this form. — ab. 



schneideri. schneideri Lampa (^ melana Clark = ? obscura Petersen) is still darker, the forewing almost unicolorous, 

 the hindwing also darkened towards the distal margin, in extreme cases where the postmedian line is no 

 longer traceable it can still be distinguished fi-om dilutata ab. melana by its more purplish tone. — ab. 

 intermedia, intermedia Clark refers to the variegated forms in which the middle of the central area remains whitish, as 

 also the subterminal line and narrow, dark-intersected bands on each side of the median area; hindwing whitish 

 to beyond the middle, then fuscous. In my experience these forms have only occurred among the subspecies 

 filiyrammaria, in which they are very prevalent; but Clark's were bred from the egg among a brood of 

 autumnata. — ab. unicinctata Strand, described as a form oi dilutata, is almost certainly an extreme development 

 from the ab. intermedia of the present species, which is the dilutata of the Scandinavian authors. Very dark 

 with a very distinct white-grey median band. Two examples were taken in a birch-wood together with many 

 other forms of autumnata. If Stranu has ignored tlie other wiiitish markings it may prove synonymous with 

 the preceding. — gueneata Prout ( = autumnata Guen.) is a local race peculiar to Central France. The ground- 

 colour is dirty white as in the type form, but the lines are in part obliterated, being only well expressed 

 costally; the black marks on the veins are on the contrary intensified. It varies very little. I have seen 



tunkunata. examples from the Sand collection. — tunkunata B.-Haas; from the Sajan district, Siberia, described as a 

 variety of dilutata, will no doubt prove to belong here, as the wings are said to be glossy, bhie-grey (blackish 

 mixed) and with the subdorsal ( ? median) vein mostly strongly blackened in the middle of the wing. The 

 median area of the forewing is in general very weakly marked, but usually dark-marked costally. Hindwing 

 white-grey, with regular, sharply marked antemarginal line. The peculiar blue-grey colouring is liable to fade 

 in old specimens. — filigrammaria H.-Sch. (= polata Westw. nee Hbn.) is a small moorland form, or possibly 

 distinct species, with a narrower-winged ?, its distal margin being usually more oblique and the hinder angle 

 more rounded off. It vai'ies greatly but is on an average darker than autumnata, Ihe dark markings being 

 usually increased and intensified although the pale parts usually remain whitish. The white hindwing is nearly 

 always more strongly marked than in autumnata, bearing a pair of distinct curved lines near the distal margin 

 and generally more or less dark shading between these and the margin. In the type form the entire median 

 area is dark, forming a solid central band. It is not rare. The commonest form, however, corresponds 

 (except in its smaller size) to autumnata ab. intermedia, filiyrammaria is locally common on the moors of 



unicindata. 



gueneata. 



filigram- 

 maria. 



