480 
THE OCEAN WORLD. 
Ckabs and Cbaw-Fish. 
Crabs and lobsters may be regarded as the chiefs or lords of the 
Crustacean tribes. The crabs have very large claws and smooth backs ; 
the last have small claws and the back covered with spines. Tiberius 
Caesar had the lace of a poor fisherman scratched by the rugged shell 
of a craw-fish. 
Lobsters, especially, have an amazing fecundity, and yield an im- 
mense number of eggs, each female producing from 12,000 to 20,000 
in the season. The crab is also very prolific. These eggs are, in the 
lobster, arranged in packets, which are attached to the lower surface 
of the tail, to which they are connected by a viscous substance. The 
manner in which the hen lobster disposes of her burden is curious 
and interesting. Whether she bends or stands erect she is able to 
hold it obscurely or expose it to the light. Sometimes, according to 
Coste, the eggs are left immovable, or simply submerged; at others 
they are subjected to successive washings by gently agitating the 
false claw which shelters them from right to left. When first exuded 
from the ovary the eggs aro very small, but they seem to increase 
during the time they are borne about under the tail, and before they 
are committed to the sand or water they have attained the size of 
small shot. The evolution ol the germ is in progress during si£ 
months. At the moment of exclusion the female extends the tail, im- 
presses upon the eggs an oscillating motion, in order to destroy the 
shell and scatter the larvae, delivering herself in two or three days of 
her entire burden (Coste). “As the young lie enclosed within the 
membrane of the egg,” says Couch, « the claws are folded on each 
other, and the tail is flexed on them as far as the margin of the shield- 
Ihe dorsal spine is bent backwards, and lies in contact with the dorsal 
shield, for the young when it escapes from the egg is quite soft ; but it 
rapidly hardens and solidifies by the deposition of calcareous matter ou 
what may be called its skin.” 
As soon as born, the young Crustaceans withdraw from the mother 
and ascend to the surface of the water, in order to gain the open sea- 
They swim in a circle ; but this pelagic life is not of long duration > 
they quit it after their fourth moult, which takes place between the 
thirtieth and fortieth day, at which time they lose the transitory organ® 
