210 



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 (Mysidoe) the eggs are carried in 

 one or two oval pouches beneath the thorax ; while in the 

 curious little Water-fleas (Cyclopidce), 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 leDgth 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 (Carcinus mcenas). 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 ; the eyes are without stalks ; there are two 

 pairs of jointed feet, ending in tufts of stiff bristles ; and 

 a long jointed body carried straight behind, which 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 he 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 creature, 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 

 Cab, comme ilfaut. j£ 



This periodic casting of the skin is a needful provision 



