CRAYFISH, LOBSTERS, SPIDERS, AND INSECTS 139 



plex and interesting. 

 From tlie egg tliere 

 hatclies a peculiar form, 

 having a long abdomen, 

 few or no appendages, 

 and large compound 

 eyes. This is the larval 

 form and is called zoea 

 (Fig. 78). After molt- 

 ing several times, the 

 larva changes to a form 

 called megalops (Fig. 79). 

 This form somewhat resembles 



FlQ. 79. — Megalops of a crab. 



Fig. 78. — Zoea of a crab. 



the adult crab. Finally, 

 the form, megalops, 

 gradually changes, by 

 additional molts, into 

 the adult crab. 



The common blue 

 crab, found along the 

 Atlantic coast from 

 Cape Cod south, and 

 I in the Gulf, is our 

 most important edible 

 crab. The so-called 

 " soft-shelled " crabs 

 are simply blue crabs 

 that are caught just 

 after they have cast 

 theoldhardskin. The 

 body is then soft and 

 the flesh is considered 

 a great dehcacy. 



