sos) [xxvili, xxix 
Upon Dr. Chapman’s suggestion that butterflies assume a 
position with their heads directly away from the sun in order 
to receive as much heat as possible, the speaker wished to point 
out, that when the wings are raised over the back, this was 
the very position which insured a minimum of heat. The size 
of the shadow cast is a criterion of the amount of heat inter- 
cepted and in this position with the wings upright the shadow 
becomes a mere line. When the wings of a butterfly resting 
in this position on the ground are fully opened, there is, it is 
true, some very slight compensating gain of heat, wherever 
the sun’s rays strike the earth obliquely. The head of the 
butterfly being turned from the sun, the raised costal margins 
of its fore-wings insure that the heat rays strike the plane of 
the wings with slightly less obliquity and therefore with more 
thermal effect than they do the ground. 
Referring to the “list” of butterflies in the resting position 
Professor Poulton said that, on one occasion many years ago, - 
he had observed this movement in a pronounced degree in the 
Green Hairstreak (Thecla vubi). The butterfly was observed 
at rest on the flat surface of a leaf at Birdlip, Gloucestershire, 
and it let itself down on one side so completely that it seemed 
to lie flat on the leaf. The obliteration of shadow was very 
marked and had at the time forced itself upon the speaker’s 
mind as the significance of the attitude. 
Dr. F. A. Dixey said that he was much struck with the fact 
pointed out by Dr. Longstaff, that there were several hours of 
daylight during which most butterflies were inactive, and were 
therefore fully exposed in the resting position to the attacks 
of insectivorous enemies. This could hardly fail to have an 
important influence on their postures and colouring. To the 
evidence lately adduced in favour of the selection by butterflies 
of appropriate surroundings for their concealment during 
morning, as late as two hours after sunrise (which occurs in Patalung 
between five and six o’clock),” rests ‘‘ motionless in the angle formed by 
the leaves with the stem” of its favourite plant. These same larve are, 
he states, extremely active during the heat of the day. As possibly bearing 
upon these habits the author remarks that ‘‘ The hour immediately pre- 
ceding and following upon sunrise is the time of the greatest activity of 
many Malayan animals, for both nocturnal and diurnal species are often 
then at work.” At the same time, Mr. Annandale is careful to point out 
that nothing is ‘‘ known as to the enemies and dangers to which this 
particular insect is exposed.” [E. B. P.] 
