MOULTING. 155 



tcrvals, the removal of the old crust being necessary to admit of 

 the growth of the animal. In the early stages of life, when growth 

 is most rapid, the change takes place at intervals of only a few 

 weeks' duration ; but as the animal advances in age, the shell is 

 cast with less and less frequency, and there is reason to believe 

 that after a certain period the moults cease altogether. All parts 

 of the animal immediately expand on being liberated from the old 

 crust, between which and the new one there is always a very 

 perceptible difference in size. 



The most curious thing in this moulting of the Crustacea is the 

 remarkably perfect condition in which the old crust is thrown 

 off; the covering of every part of the body and its appendages 

 being left whole and entire, so as to give the rejected crust a 

 striking resemblance to the animal itself. In the ordinary Crabs, 

 indeed, no unpractised eye could detect the difference, and the 

 uninitiated observer who finds the empty shells of one of these 

 animals in his Aquarium is pretty sure to look at it regretfully 

 as the dead body of one of his pets ; and very frequently the 

 mistake is not discovered until some hours, or it may be a day or 

 two afterwards, when, to the utter confounding of the owner, the 

 animal which was supposed to be dead and gone is again seen 

 stalking about, a veritable ghost. A similar mistake sometimes 

 occurs with the Hermit Crab ; but in this case, unless there be 

 some other carnivorous inmate of the Aquarium to account for 

 the disappearance of the fleshy tail, the observer is considerably 

 perplexed at the absence of that important part of the Hermit 

 Crab's structure. 



Our own first acquaintance with the moulting of the Hermit 

 Crab was made under circumstances which rendered this disap- 

 pearance of the body doubly perplexing. There were two 

 Hermit Crabs confined by themselves in a dish ; but they were 

 by no means neighbourly, and seldom met in their walks without 

 having a spar, which sometimes took the form of a regular fight. 

 One morning they both lay dead (as it seemed) at the bottom ol 

 the dish ; and most unaccountably, in both alike, the fleshy body 

 was clean gone. It was the tragedy of the Kilkenny cats over 

 again, with the difference that in this case the tails were the only 

 parts eaten. What could it mean? The mystery was soon ex- 

 plained. There, amongst the weeds, at the side of the dish, were 

 the real Hermit Crabs, still alive, winking and blinking ; and 



