READING RIDDLES OF THE ROCKS 135 
entirely, of small, irregularly hexagonal horny 
scutes, slightly thickened inthe centre. The 
quarries of lithographic stone at Solenhofen 
have yielded a few specimens of flying reptiles, 
pterodactyls, which not only verify the correct- 
ness of the inference that these creatures pos- 
sessed membranous wings, like the bats, but 
show the exact shape, and it was sometimes 
very curious, of this membrane. And each and 
all of these wonderfully preserved specimens 
serve both to check and guide the restorer 
in his task of clothing the animal as it was in 
life. 
And all this help is needed, for it is an easy 
matter to make a wide-sweeping deduction, 
apparently resting on a good basis of fact, and 
yet erroneous. Remains of the Mammoth 
and Woolly Rhinoceros, found in Siberia and 
Northern Europe, were thought to indicate 
that at the period when these animals lived 
the climate was mild,:a very natural inference, 
since the elephants and rhinoceroses we now 
know are all inhabitants of tropical climes. 
But the discovery of more or less complete 
specimens makes it evident that the climate 
