MARINE BIOLOGICAL STATION AT POET ERIN. 107 



or both the great claws, which can, however, be replaced 

 after a time. Little is known as to the food of the lobster 

 when at large in the sea. In captivity it readily takes 

 pieces of fresh fish, in search of which it is apparently 

 guided by the sensory antennules, by smell rather than 

 by sight. 



Growth takes place only when the shell is cast and 

 while the new shell is hardening. Casting occurs about 

 every seventh day during the first few weeks of life, but 

 less and less frequently as age advances. When the shell 

 is cast the soft membrane between the shell covering the 

 fore part of the body and that of the tail splits. The 

 fore part of the body is then withdrawn from the shell, 

 and carries with it the great claws, walking legs, feelers, 

 jaws and other appendages of the mouth, and the lining 

 of the stomach with its horny grinding teeth. Finally 

 the tail is withdrawn and the lobster is free. The new 

 shell is formed beneath the old one, and is at first quite 

 soft. The majority of adult lobsters cast in the months 

 of July, August and September. Should one of a number 

 of lobsters confined together in a tank cast its shell it is 

 almost invariably attacked and severely mutilated by the 

 others. Growth is slow : a lobster 9 to 10 inches long is 

 probably four to five years old. 



The female lobsters spawn during the months July, 

 August, September and October, and a specimen 11 to 12 

 inches long will produce 11,000 to 12,000 eggs. These 

 are attached to the swimmerets of the tail, and are there 

 carried until the following year, the majority hatching 

 out during a period which corresponds pretty closely 

 with that of spawning. The young are at first free 

 swimming, and pass through a succession of changes of 

 structure before the adult condition is reached (figs. XYI. 

 and XVII.). 



