Exuviation in Shrimps and Lobsters. 171 
the carapace to the abdomen is burst, and this great dorsal plate is 
raised. Some degree of rest follows these first struggles ; but after 
a short time the animal again puts all its organs in motion, the ca- 
rapace is seen to rise gradually from the legs beneath, and in less than 
half an hour, the animal has extricated itself from this portion of 
its slough. By retracting its head, the antennae, eyes, and legs are 
withdrawn as from a case ; and the extrication of the last, being the 
most difficult and complicated operation, is attended with so much 
pain, that the effort sometimes occasions the loss of one or more of 
the organs. The hinder parts are withdrawn with less difficulty ; 
the head is conducted below the carapace, and the tail being thrown 
off by a forward motion attended with a brisk and distensive action, 
the creature is seen divested of all its encumbrances, and the case is 
left unbroken, as if no struggle had ever taken place within it. 
I have no doubt that the process here described in the Cray-fish 
corresponds to what takes place in the common prawn (Palaemon 
serratus, Leach,) although I have never been able to observe it in 
operation ; the following is a description of the case from which the 
animal has recently extricated itself : The whole is thin, elastic and 
transparent ; the carapace with its serrated process whole, the an- 
tennae perfect to their minute extremities : the palpi and jaws drawn 
within the cavity of the thorax, and partially separated from the 
sternal plate ; the latter with the legs still forming a loose attach- 
ment to each other, and without fracture, but drawn somewhat pos- 
teriorly into the thoracic cavity. The case and pedestal of one eye 
were within the thorax, but the other could not be found ; the legs 
perfect, and attached to the sternal plate. The caudal plates were 
united at their joints, but in no part was there any intervening mem- 
brane, this portion of the body not appearing to be thrown off with 
the more solid covering : a circumstance which will account for the 
fact, that the eyes do not long remain attached to the adjacent parts 
after the slough is left by its inhabitant. 
The habits of the Lobster (Astacus Europeus, Leach,) at this pe- 
riodical crisis, and the circumstances attending it, present a very 
considerable difference from those of the species already mentioned. 
So far from abstaining from food, it is not uncommon for it to be 
taken in crab pots, which it has been enticed to enter by the allure- 
ment of the usual bait; and instances have been related to me, where, 
when the fisherman commenced to handle his capture, the animal has 
slipped away, leaving an empty husk as the only reward of hislabour. 
It was by a circumstance somewhat similar that the opportunity is 
afforded me of giving a minute description of a very perfect case, 
