9 
dealt with at length. All these had, in one or other of the humid dis¬ 
tricts to the north or west of the British Isles, a form with dark ground 
colour crossed by transverse lines, the ground colour becoming whiter 
and the transverse lines coalescing into banded form as more open, 
drier, southern or eastern localities are reached. In the north and 
west of Scotland, and in some parts of Ireland, the prevailing form of 
M. fluctuata is dark grey in colour, with transverse lines, the central 
area often being without the slightest tendency for the transverse lines 
to assume a banded form; but as we come south the ground colour 
becomes paler in some localities, and at the same time the central band 
necessarily becomes more marked, until in the south of England and 
on many parts of the Continent, the ground colour has become white, 
and the central band partly disappears, often forming only a small dark 
blotch on the costa, or being entirely absent. Occasionally dark 
specimens and completely banded forms are captured, but these must 
be looked upon as simply reversions to the darker form. M. montanata, 
taking the Hebridean and Shetlandic forms as nearest to the type, 
shows a similar development, and the manner of suppression of the 
central area of the band shows most clearly in a long series from various 
localities. The special development relative to M. rubiginata was also 
entered into; a comparison of the Lancashire and south coast forms of 
M. galiata was made, and the darker ground colour and central band 
of the northern form noted. C. bilineata has a dark ground colour and is 
crossed by dark transverse lines in the majority of Shetland specimens ; 
Scotch specimens also tended to be dark in many localities; as we got 
farther east and south there was a greater tendency for both sexes to 
become golden, yet in many southern localities, and in some years more 
than others, a large percentage showed reversion, by developing a dark 
central band, more or less complete. These dark specimens in the 
south were nearly always females, and hence this threw a side-light on 
sexual dimorphism in this group. Mr. Tutt suggested that it was quite 
open to assume that the paler forms were older (although he did not 
think it possible), when the dark specimens would have to be considered 
as instances of progressive development, instead of, as he had done, 
looking upon the dark forms as older, and the gradual extinction of 
transverse lines and bands, and change of ground colour, as so many 
steps in the line of progressive development. 
Dr. Buckell remarked on M. ocellatci , Coremia ferrugata , C. unidentaria, 
C. propugnata , and C. munitcita, whilst Messrs. Clark, Milton, and 
Battley took part in the discussion which followed ; and a vote of thanks 
was accorded to Mr. Tutt for his paper. An interesting discussion also 
took place respecting the effect of the recent severe frost on aquatic 
coleoptera and fish. Mr. Milton stated that he had found large 
numbers of dead beetles in the shallow pools at Clapton; but in the 
deeper ponds they appeared to have survived. Several members had 
observed dead fish floating on ponds and lakes, the oxygen in the water 
having apparently become exhausted. 
February igf/i, 1891.—Exhibits : Mr. Clark, Noctuaconflua, bred from 
ova; larvae of Cossus ligniperda , showing the pale form usually obtained 
in the spring; also a photograph of a white frog. Mr. Battley, 
varieties of Chelonia caja . Mr. Milton, Xanthia si/ago , Cidaria 
C 
