APPENDIX. 99 



appendages. The greater size and more vigorous swimming causes 

 this stage to be easily distinguished from the preceding stages. 



Four days is the average duration of this stage at Wickford. 



Fourth Stage. (Plate XII.) The lobster at this stage becomes 

 shaped like the adult. The claws are carried in front while swim- 

 ming. The thoracic swimming appendages become reduced and 

 functionless, and in general the unmistakable resemblance to the 

 adult easily determines this stage from the preceding ones. The 

 swimming is now very vigorous, and, when swimming in the rearing 

 car, it always heads toward the current. Burrowing is begun to a 

 certain extent in this period. 



The average number of days required at Wickford to reach this 

 stage from the time of hatching is thirteen. 



10. ADOLESCENT PERIOD. 



Later stages develop other structural changes, although more 

 gradually. At the seventh stage the appendages on the first abdomi- 

 nal segment appear as buds, and by the eighth stage they have de- 

 veloped sufficiently to enable the sex to be told. Beyond this 

 stage the changes consist merely in the gradual assumption of the 

 mature form and structure. 



11. SOME PECULIAR MEANS OF SELF-PRESERVATION. 



Any one who has handled lobsters under 3 inches in length is 

 familiar with the fact that the little fellows, when handled, will 

 straighten out and to every appearance seem to be dead. The 

 rigidity does not cease immediately when replaced in the water. 

 This death-feigning habit is gradually outgrown, and perhaps is never 

 found among adult lobsters. It is supposed to be useful to the 

 animal in protecting itself against fishes which prefer live food. 



Autotomy, the voluntary shedding of an appendage, is another 

 habit which is more easily seen to be self-preservative. If a lobster's 

 claw is held too tightly or crushed, it is almost always quickly dropped 



