262 CRUSTACEA, ECHINODERMS, ETC. 



limb, or has one torn off in a fight. This difficulty is 

 got over by a new one budding. Mr. Lloyd speaks 

 of the general moulting as follows in his capital little 

 ' Handbook to the Crystal Palace Aquarium ' : 



" This moulting is necessary because the shell once 

 formed never grows larger, and therefore as the 

 creature within increases in size, and a new shell in a 

 soft state begins to be formed below the old one, the 

 latter becomes too small. The lobster is aware of 

 this, and of its approaching moult, and instinctively 

 knowing its utter helplessness from the attacks of its 

 fellows, or from other animals during the quarter or 

 half hour occupied by the disengagement of its shell, 

 and while it is more or less soft for a few days after- 

 wards, it, in an aquarium, sets about making a regular 

 fortress, choosing its position with great judgment, 

 usually beneath a shelving rock, with rock on each 

 side, and with a kind of " earthwork " thrown up de- 

 fensively in front, composed of the sand and shingle 

 which have been removed from the hole in which it 

 burrows, and here, ever on the watch for intruders, it 

 patiently awaits its change of coat. Occasionally, when 

 this fortification cannot be made, the lobster seeks a 

 less perfectly protected place on a plateau of rock 

 close to the water's surface, and therefore not often 

 visited by other animals. When the time at last 

 comes, it throws itself on its side, and ruptures the 

 skin connecting the body with the first ring of the 

 abdomen, and this is the only part intentionally 



