201 LIFE, IN ITS INTERMEDIATE FORMS. 
posited on the false feet, and are carried about by the 
female parent until near the period of hatching. In some 
of the Opossum-shrimps ( My sides ) the eggs are carried in 
one or two oval pouches beneath the thorax ; while in the 
curious little Water-fleas ( Cyclopidw ), and the still more 
remarkable Epizoa, the eggs are carried on each side of 
the tail in two oval or cylindrical bags, generally of large 
size, and sometimes of such length as to exceed that of 
the whole animal besides. 
Like Insects, the Crustacea undergo a metamorphosis — 
perhaps with one or two exceptions. No one, uninstructed, 
could possibly recognise the earliest stage of the common 
Shore Crab (Carcims mcmas). A hemispherical carapace 
or shell, not so big as a small pin’s head, sends up from 
its centre a long, pointed, curved spine, while another 
spine curves downwards from the front beneath the body 
like a beak ; tho eyes aro without stalks ; thero are two 
pairs of jointed feet, ending in tufts of stiff bristles ; and 
a long jointed body carried straight behind, winch ends in 
two bundles of diverging spines. Such is the grotesque 
character under which our little masquerader makes his 
“ first appearance on any stage.” After a time ho drops 
his outer garments, and assumes a second form — widely 
different from the former, and still sufficiently remote 
from the ultimate one \ and it is not till the third moult 
that the little creatui'e, now grown to the size of a hemp- 
seed, begins to be recognisable as a Crab ; though even 
now he has several stages to pass through, several doffings 
of coats and trousers, before he is quite a proper Shore 
Crab, conmc il faut. 
This periodic casting of the skin is a needful provision 
