CRUSTACEA, 515 
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 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 species of crabs are numerous, and they vary in size. The 
y 
Fig. 344.—Corystes Cassivelaunus, female. 
long-clawed crab (Corystes Cassivelaunus) of Pennant and Leach 
(Fig. 343) is remarkable for its long antennz, which considerably 
exceed the body. The foot-jaws have their third joint longer than 
the second, terminating in an obtuse point, with a notch on its 
interior edge ; eyes wide apart, borne upon large peduncles, which 
are short and nearly cylindrical; anterior feet large, equal, twice the 
length of the body, and nearly cylindrical in the males; in the 
females (Fig. 344) about the length of the body, and compressed, 
especially towards the hand-claw. The other feet terminate in an 
HH 2 
