86 FIRST LESSONS IN ZOOLO&Y. 



moult, or cast its skin, the shield splits from its hind edge 

 as far as the base of the beak, where it is too solid to sepa- 

 rate. The lobster then draws its body out of the rent. 

 The claw — at this time soft, fleshy, and very watery — is 

 drawn out through the first joint, part of which disappears 

 at this time, so as to make room for the passage of the 

 flesh of the big claw. In moulting, the stomach, with the 

 solid teeth, is cast off with the old crust or skin. 



Haying looked with some care at the lobster, we can 

 glance more hastily at some of its allies. Its nearer rela- 



Fia. 90.— Young, or Zoga, of Cancer irrora- Fig. 91. — Megalops, or older stage, 

 tus. (Highly magnified.) of Fig. 90. (Magnified.; 



tions are the crabs, and of these there are many kinds. In 

 crabs the hind body is very small and folded to the under 

 side of the chest. The common shore-crab (Fig. 89) lives 

 under stones, where it may be found at low-water mark. 

 When the tide comes in it may be seen running sideways 

 in a comical fashion over the bottom. 



If we compare the crab with the lobster we see a great 

 advance; the crab's head and mid-body are much better de- 

 veloped, while its hind body is small and folded to the un- 

 der side of the chest. There is a transfer of parts head- 

 wards, a great step onwards and upwards. 



