ann cans WareRs 159 
fend for itself. Indeed, the young crayfishes 
that have begun to swim about often seek the 
shelter of the mother’s tail, as chickens the hen’s 
wings. This shortening down of the chapters 
of the life-history is an adaptation that tends 
to circumvent some of the dangers of youth. 
The time taken to grow up may vary even 
among the same animals according to the sea- 
son, and may be very different in two closely 
related species. There occurs throughout Cen- 
tral Europe a larger cousin of our common 
newt, known as the “fire-salamander,” from 
the large splashes of orange colour on its black 
body. It brings forth its young alive, but still 
surrounded by the egg envelope, which bursts 
at once, setting free a gill-bearing tadpole. 
This little creature does not take on the sala- 
mander form, or leave the water until it 1s 
about three and a half months old. But if the 
summer is dry, and the water in the pools gets 
low, the stages are gone through more rap- 
idly, and development may be complete at the 
end of two months. This salamander is not 
found at a greater height than 2500 feet. 
Above that its place is taken by another very 
similar form without the orange spots, known 
as the black salamander. This form may 
