CASTING ITS SHELL. 221 



effluent ducts opening at the base of one of the pairs of 

 the thoracic legs. Through these passages the ova, des- 

 tined for the future multiplication of the species, descend 

 to be excluded and arranged under the tail. 



The young in their larval state are very imperfect ; nor 

 is the form proper to the adult attained until after several 

 moults, constituting a complete metamorphosis, though 

 one effected by very gradual stages. In a few weeks, 

 however, their shells acquire firmness and solidity, and 

 become useful as offensive and defensive armour. 



The most remarkable, and, so far as the creature itself 

 is concerned, the most disagreeable incident in the lob- 

 ster's life is its annual exuviations. Like the crab, it 

 sheds its shelly covering every year. Previous to the 

 change it seems to be sick, uneasy, languid. It ceases 

 to harrow up the sand and prowl about for prey, and 

 lies almost motionless and semi-torpid, as if dreading the 

 impending trial. The new shell is developed in three or 

 four days, if, during the period of its defencelessness, it 

 has not fallen a prey to some one of its many enemies or 

 of its own kind. The additional size which the animal 

 gains at each occasion of " moulting" is really wonderful; 

 and not less wonderful is it to see the old coat cast aside, 

 like a suit of worn-out clothes, while the creature, naked 

 and soft, awaits, in a sheltered hole or corner, the growth 

 of its new harness. It is difficult to understand, perhaps, 

 how it contrives to draw the muscles of its claws out of 

 their hard, shelly covering ; but it would seem that dur- 

 ing its sickly state the limb so contracts as to be capable 

 of being withdrawn through the joints and narrow pass- 

 ages near the body. During the first year of its age it 

 changes its shell every six weeks, in the second year 



