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 antenna;, eyes, and legs are 

 withdrawn as from a case ; and the extrication of the last, being the 

 most difficult and complicated operation, is attended w'th 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 The hinder parts are withdrawn with less difficulty ; 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 alreaciy 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, 



