47 
better protected on the dark beech trunks than the typical form, for 
when once you have been accustomed to finding them the latter can 
often be seen at rest some distance off, but the darker ones are only 
seen by most careful searching. I am a little surprised to hear that 
the dark ones are considered to be better protected than the type in the 
Reading district, but possibly the trees there assume a somewhat 
different tint from those I am best acquainted with. I know at Brent¬ 
wood the type is very well concealed. They are to be found at various 
heights from the ground, the average would be about four to five feet, 
sometimes less, and sometimes as high as ten or twelve feet. 
In looking through the Doubleday collection 1 find there are no 
dark ones whatever, and Newman has made no mention of that form, 
and as I have always heard that Newman had the late Frederick 
Bond’s collection at his disposal when compiling his “ British Moths,” 
I think we may be safe in concluding that the black form is a modern 
development. 
The habit which S. fagi has of resting with the underwings pro¬ 
truding beyond the costa of the forewing is very unusual, although it 
is not confined entirely to that species, as two or three other species 
which are of widely different genera, such as Smerinthm ocellata, 
Amorpha populi, and Eutrivha ijuercifolia, exhibit the same tendency. 
In all cases, the part of the lower wing which is exposed to view has, 
to some extent, the pattern of the forewing, but the part which is 
covered has no trace of it. I have exhibited lower wings of both 8’. 
fagi and S. ocellata. In a paper read byF. Merrifield at the Entomo¬ 
logical Society in 1899 there are some interesting observations on the 
lame of S. fagi, an extract from which I will give here. The paper 
was entitled “ Experiments and Observations upon the Susceptibility 
of Certain Lepidopterous Larvae and Pup.e to the Colours of their 
Surroundings.” It runs :—“ Mr. W. Holland and Mr. A. H. Hamm, 
of the Hope Department, who are extremely skilled and accurate ob¬ 
servers, drew my attention last year (1898) to the fact that the lame 
of this species differed in tint according as they are reared upon 
beech or birch, and that the colours are in each case such as to conceal 
them. During the present year Mr. Hamm reared two batches (from 
different parents) upon the same foodplant, beech, but in other respects 
under very different conditions as regards environment. One of the 
batches was reared in a white, tissue-lined rectangular case, with a 
perforated zinc lid, the other in a similar case, lined with black tissue 
paper. We compared the two, placing both batches on white paper, 
on July 18th, 1899. There were 24 larvae in the batch reared in tie 
white case, and of these all but two were in the last stage, and mostly 
advanced in it. All but one were much lighter than the larvae of the 
species usually met with in nature, and some most markedly lighter. 
The other batch consisted of fourteen larvae, of which ten were in the 
last stage (mostly advanced), one in the last but one, and three in the 
last but two. All were very dark, and most of them far darker than 
those generally met with in nature. It is clear that this species is 
highly sensitive, and it would be of great interest to repeat the experi¬ 
ments under conditions which have been found in other larvae to pro¬ 
duce the strongest effects. It is remarkable that such considerable 
results followed from surroundings which were not apparently in con¬ 
tact with the lame, for these, at any rate when they were examined, 
