80 CRABS AND INSECTS. 
“casting hairs” (Fig. 84). The soft-shelled crab is a re- 
sult of the casting. They also have the faculty of throw- 
ing off their limbs and renewing them again. 
Development.— The young of most crustaceans pass 
through many changes before assuming the parent form.* 
The eggs resemble at first minute currants (Fig. 86), that 
attach themselves by glutinous threads to the appendages 
* The Australian Dromia is an exception, the young leaving the 
egg in the adult form, and clinging to the mother. A similar case is 
seen in the fresh-water cray-fish (Fig. 85), Astacus fluviatilis ; the 
young of some crustaceans (Balanus) appear at first in the Nauplius 
form, with three pairs of legs, 
Fic, 85.—Astacus fluviatilis. A, two recently hatched cray-fish attached to 
one of the swimmerets of the mother ; ec, ruptured egg-cases ; B, chela 
of a recently hatched cray-fish, - 10. 
