CRUSTACEANS. 489 



becomes more solid they get less active, and finally return to the 

 bottom to cast their shell and assume a new form. 



According to the observations of M. Coste, the young lobster casts 

 its shell from eight to ten times in the first year, from five to seven in 

 the second, three to four times the third, and two or three times the 

 fourth year. In the fifth year they attain the adult state. Whence 



Fig. 335. Corystes Cassivelaunus, male. 



it follows, that the small lobsters served at our tables have changed 

 their calcareous vestment something like twenty-one times, and are 

 now clothed in their twenty-second habit. 



The crabs are numerous in species and various in size. The long- 

 clawed crab (Corystes Cassivelaunus) of Pennant and Leach (Fig. 335) 



