NOTES ON BRITISH LEPIDOPTERA. 111 
central fascia is darker grey (sometimes brownish), enclosing a 
black discoidal spot, the external half intersected by a pale wavy 
line edged internally with blackish; beyond is a white band 
traversed by a grey line, which is often interrupted ; outer mar- 
ginal area grey, frequently tinged with brown, intersected by a 
white sinuous line. Hind wing grey; the basal third contains a 
black discoidal spot, is traversed by some whitish lines, and 
limited by a white band, which is intersected by a grey line 
agreeing with that on the fore wing; white submarginal line 
wavy. Fringes pale grey, and whitish chequered with darker at 
ends of nervules, and preceded by an indistinct black line. Thorax 
dark grey, with inconspicuous black dots. 
The white band and line on the basal area of the fore wing 
vary in width, and consequently this portion of the wing is darker 
or lighter, according to the width of these markings. The 
central fascia also varies in breadth, and this to a large extent 
controls the width of the white band which follows it. In some 
specimens the central fascia is much contracted below the middle, 
and in the form known as var. degenerata, Haworth, the fascia 
is separated into two portions, the larger being the costal one. 
On the hind wings there is rather more variation, but the 
outer marginal area always corresponds with that of the fore 
wings. In some specimens the hind wings are white, with the 
basal two-thirds sparingly sprinkled with greyish, and limited by 
a transverse line of blackish dots. In others they are white, 
faintly dusted with grey, and traversed by four equidistant grey 
lines, the third dotted with black throughout its course. One 
specimen, captured by myself in Hertfordshire, has the basal 
two-thirds paler than usual, and the median nervules are marked 
with blackish as far as the limiting line, which in this specimen 
is very indistinct. 
Two characters almost invariably present in the next species 
(M. rivata) are sometimes exhibited, in a modified form, in some 
examples of M. sociata. These are the pale oblique dash from 
apex to submarginal line and the blackish longitudinal bars 
below. ‘The latter are, however, generally represented in sociata 
by two blackish spots within the submarginal line, and some- 
times obscuring it at this point. 
Var. obscurata, South, Entom. xxi. p. 27, fig. (1888). 
Fore wings deep brownish grey, the basal area limited by a 
fine whitish transverse line, not always clearly defined; the 
central band, containing a black discoidal spot, is hardly darker 
than the rest of the wing, edged inwardly by a thin whitish line, 
and outwardly by a double whitish line, which is acutely angu- 
lated about the middle; submarginal line whitish. Hind wings 
pale brownish grey, outer third much darker, limited inwardly by 
a double whitish line, and traversed by a submarginal interrupted 
whitish line, 
