40 THE NATURAL HISTORY OF THE COMMON CRAYFISH. 
After the female has received the deposit of the 
spermatic matter of the male, she retires to a burrow, 
in the manner already stated, and then the process of 
laying the eggs commences. ‘These, as they leave the 
apertures of the oviducts, are coated with a viscid matter, 
which is readily drawn out into a short thread. The 
end of the thread attaches itself to one of the long hairs, 
with which the swimmerets are fringed, and as the viscid 
matter rapidly hardens, the egg thus becomes attached 
to the limb by a stalk. The operation is repeated, until 
sometimes a couple of hundred eggs are thus glued on 
to the swimmerets. Partaking in the movements of the 
swimmerets, they are washed backwards and forwards in 
the water, and thus aérated and kept free of impurities ; 
while the young crayfish is formed much in the same 
way as the chick is formed in a hen’s egg. 
The process of development, however, is very slow, 
as it occupies the whole winter. In late spring-time, or 
early summer, the young burst the thin shell of the 
egg, and, when they are hatched, present a general re- 
semblance to their parents. This is very unlike what 
takes place in crabs and lobsters, in which the young 
leave the egg in a condition very different from the 
parent, and undergo a remarkable metamorphosis before 
they attain their proper form. 
For some time after they are hatched, the young hold 
on to the swimmerets of the mother, and are carried 
about, protected by her abdomen, as in a kind of nursery. 
