540 
BIONOMIC NOTES 
though the approximate spot may have been carefully noted. I 
have watched the fly, immediately after pitching, alter its position so 
that its axis is directed towards the sun, thus casting no shadow.” 1 
When in India in 1903 I several times noticed that when a 
butterfly with a cryptically coloured underside rested on a flat 
surface, the shadow cast by it was often far more conspicuous than 
the butterfly itself. Obviously, therefore, in such a case economy 
of shadow might afford considerable protection. 
Now, near Simla, in October, 1903, when watching Pararge schakra , 
Koll., a butterfly resembling P. megaera , I noted three individuals 
in succession settled with their tails to the sun so as to reduce the 
shadow to a mere line. This was unfortunately just as I was leaving 
the district where the species occurred, but I did not observe any 
instances to the contrary. These observations were made quite 
independently of Mr. Green, and possibly at about the same time. 
During my visit to Algeria in the spring of 1905, the subject of 
heliotropism was further investigated, and my results were com¬ 
municated to the Entomological Society shortly after my return :— 
Following up my observations on the attitude at rest of Pararge 
schakra , made near Simla, in October, 1903, I paid a good 
deal of attention in February and March of the present year 
(1905) to P. meone , Oram., a butterfly that I found in varying 
numbers in all the parts of Algeria that I visited. This is 
either a Southern form of P. aegeria, Linn., or a closely allied 
species in which the yellowish spots are replaced by fulvous. 
It is fond of settling on sandy roads, rocks, walls, or the leaves 
of trees or shrubs, comparatively rarely visiting flowers. It 
first pitches, invariably I might say, with its wings about three- 
quarters expanded, and, almost always with its head turned 
away from the sun, the axis of the body being rarely more 
than 45° to either side. Immediately after settling it more 
often than not adjusts itself, by a quick movement, so as to 
make its tail point fairly accurately to the sun. After this 
adjustment, if at all, it closes its wings over its back, and 
as a necessary result its shadow is reduced to, or approximates 
to, a mere line. There can, I think, be no doubt that this habit 
is a great protection to the insect, since when resting on fairly 
flat surfaces the shadow of a Satyrine or Nymphaline butterfly 
with cryptic underside is often more conspicuous than the fly 
itself. 
1 “ Notes on some Ceylon Butterflies,” Spolia Zeylanica, vol. ii., pt. vi., 1904, 
p. 76. 
