THE MERA COLLECTION OF BRITISH LEPIDOPTERA. 127
fourteen Ghost Swifts (H. humuli) from the Shetlands; these
are the well-known aberration (var. hethlandica) confined to that
area, in which the male assumes to a greater or lesser extent
the colour and markings of the female. There are four speci-
mens of the Six-spot Burnet (Z. filipendulae)—one from Col-
chester)—in which the spots are yellow instead of red = var.
flava. The Crimson Speckled Footman (D. pulchella), a rare
migrant, is represented by two specimens, one of these was
taken by Mr. Mera himself at Felixstowe in 1892. The occur-
rence of the Wood Tiger (N. plantaginis) at Ipswich is interesting
as it is very scarce in the Eastern Counties.
Mr. Mera had acquired by purchases at sales the comparatively
long series (10) of the extinct Reed Tussock Moth (L. coenosa);
this exclusively fen insect died out about 1880. The Scarce
Vapourer (O. gonostigma), which has a wingless female like the
Common Vapourer (O. antiqua) is an interesting Essex insect,
Brentwood, where those in the collection hail from, being one
of the few localities where it can be found. Another acquisition
by purchase is the Small Lappet (G. ilicifolia), formerly occurring
at Cannock Chase. There are six of the very local and rare
Scarce Hook-tip (D. sicula) only known from the Bristol district.
The series of The Lobster (S. fagi) is very interesting, as it
exhibits the development of pronounced melanism in Epping
Forest in recent years. Mr. Mera drew attention to this in a
paper in The London Naturalist for 1925. Another recent
instance of change to a melanic form is shown by a specimen
of the Lesser Satin Lutestring (C. duplaris), also from Epping
Forest. The Silver Cloud (X. conspicillaris), a rare species, is
represented by a series of eleven, bred from Taunton, and
another rare immigrant, the Lesser Mottled Willow (L. exigua)
by a specimen taken at Mucking in 1906, a year witnessing
a big influx of this species.
The Rosy Marsh (N. subrosea) has been extinct in this country
since about 1850, when the fens it inhabited were drained; the
three specimens in the collection are in fair condition. The
Northern Drab (T. opima) is somewhat of a misnomer, as it
occurs in Southern localities also, among which Wanstead was
formerly a prolific one. Mr. Mera and his sons used to find it
commonly on the Dwarf Sallows on Wanstead Flats up to 1920,
and the long series from that locality is a very variable one.