966 THE GEELONG NATURALIST. 
. A proof of the earth's former liquid condition is afforded by- 
the flattening at the poles. The older rocks also show abundant 
evidence of fusion. When the earth was in this molten state, it: 
was surrounded by vapour, which on cooling formed rain until the 
whole surface became covered with water. The crust being thin, 
fractures would be frequent and parts would be thrust above the 
water, but would soon be washed back. The characteristics of this 
eriod are shallow seas with warm waters, little islands, and soft- 
bodied animals. 
In studying the Lower Silurian system we find immense rents 
running in the direction of the magnetic meridian, and a few 
running at right angles to it. The latter are filled with granite, ` 
basalt, ete., while the precious metals are found in the meridian 
reefs. Therefore we may infer that the schistose rocks were- 
deposited prior to the formation of the quartz within its reefs, that 
the quartz was slowly deposited within the reef walls by crystalli- 
sation, and that the metals associated with the quartz were slowly 
abstracted from the sea-water by the aid of electric currents assisted! 
by the heat of the water. This would explain why gold is not found 
in granite, slate, or sandstone. 
wail 
A QUEER CUSTOMER. 
Bx H. L. Grieve. 
Or all the forms of life that thronged the earth in past ages, the 
Pterodactyl, or winged: lizard, of the Jurassic period was the most 
wonderful. From the many remains of this curious lizard that of 
late years have come to light, we can form a fairly accurate idea of 
its form and even of its habits. Imagine a crocodile’s head with 
its rows of strong sharp teeth on a long and somewhat thin neck, 
and attached to a great body of enormous strength—a beast that 
could walk and fly and, perhaps, swim. The remains of a great 
number of species have been found—some scarcely larger than the 
common sparrow, while others rival the condor in size. 
_ Like the bat its wings were formed of a strong membrane, 
stretched between the bones of the hand and the arm, but there is 
a difference; in the bat the fingers are very long and the thumb is 
short, while in the pterodactyl the thumb and the next three fingers 
are short, but the little finger is as long as the body. The muscles 
on the lengthened finger must have been of enormous strength to 
support the body. 
