860 Marvels of the Universe 
One is that of the Comma, whose under-side is a speckled grey-brown, and the other is the 
pale Brimstone. In the first, the uneven edge of the wing accentuates the ragged appearance 
of a leaf. This is a not unusual form of mimicry which many species have adopted, in- 
cluding the Tortoiseshell and the Peacock. The Brimstone was photographed when hibernating in 
a holly bush; very cleverly it was concealed, for the dull yellow colour and the pointed edge 
of the wings produced a perfect resemblance to a sapless holly leaf which was ready to fall from 
the bough. 
But the most striking example of protective resemblance is that of the Indian Leaf Butterfly. 
The expanded wings are a beautiful combination of dull orange and dark golden browns, with 
a strong violet iridescence ; but when the wings are closed, as in the illustration on the opposite 
page, the similarity to a dried leaf is remarkable. 
The dull brown colour, the strong veining, even 
the little discolorations such as are to be found 
on a decaying leaf—all have been carefully 
imitated; while the butterfly’s under-wings are 
provided with a short tail, which when the 
wings are closed, does duty for the short stalk 
attaching the leaf to the stem, and completes the 
deception. 
DHE CRUSID OF PED SAKE 
BY EDWARD A. MARTIN, F.G.S. 
IMMEDIATELY the earth was sufficiently far 
from, and disconnected with, the sun to 
radiate away from itself more heat than it 
was generating or receiving, there commenced 
that slow and tremendously gradual process 
known as the formation of a crust. You 
can watch the formation of a crust in a very 
homely way, by observing the cooling at the 
surface of a pot of cobbler’s wax, or on the 
top of a pannikin of porridge, when the heat 
beneath is slowly withdrawn, the crust form- 
ing as soon as it fails to receive as much heat 
Photo by) [A. 2. Tonge. 
THE PALE BRIMSTONE BUTTERFLY. : f 
The Butterfly is here shown hibernating in a holly bush, as it 1s sending off into the alr above. But 
where the sharply-pointed wings and the pallid hue of Nature was more irregular in her actions. The 
yellow-green resemble a faded _ holly leaf; the drooping 
position of the wings also assists in the deception. seething mass of molten rock, as it was 
whirling round in space, and whirling round the sun at the same time, whilst it already began to 
bulge at the equator, was subjected to great waves of a tidal nature , and as soon as a crust was 
formed in one place, the pressure beneath of the shifting contents would here and there break 
through the tender crust again and again, and only after the lapse of an enormous period of time 
would the loss of heat cause such a crust to form as to enable it to make a secure stand against 
the tremendous assaults made upon its internal concavity. Even now, as we know, the crust is still 
liable to be broken through, and the weak parts of the earth’s surface follow well-recognized lines 
which contain the world’s volcanoes. 
When once the crust-forming influences obtained the upper hand, nothing was possible that 
could interfere with the process going forward. Whatever rival schools may say, the earth did cool, 
and a crust did eventually form. Sometimes, no doubt, portions of the crust would disappear into 
