COMMON LOBSTEE AKD SHORE CRAB. 31 



the sloughing of the common freshwater Crayfish (Astactis flti- 

 viatilis) . 



It was witnessed in the common edible Crab {Cancer' Pagurus) 

 by Mr. Couch, in 1833. 



Subsequently the moulting-process was observed by Mr. Gosse, 

 in the Spinous Spider-crab (^Maia Squinado). 



Beyond these three recorded examples, I believe that the actual 

 operation of movilting in Decapods has never been seen, though 

 the sloughs of our common Crustacea, and the animals themselves 

 but recently emerged from their old shells, are familiar to all 

 marine zoologists. 



There is no recorded account of the moulting of the Lobster, 

 that I have been able to discover. 



The Lobster from which the slough was obtained, and whose 

 operations are the subject of this communication, was an inhabit- 

 ant of a large marine aquarium in the Museum at Scarborough. 

 The period was July 1857. The aquariiim contained the ordinary 

 assemblage of sea-shore animals, and a considerable collection of 

 vegetation, which consisted of Ulva, Fticus, and other common 

 sea-weeds. 



For two days previous to its throwing off the shell, the Lobster 

 was observed in a very peculiar attitude, and to be very busily en- 

 gaged. Its abdomen was permanently and stiffly erected and 

 straight ; while the animal, in this rigid attitude, was hard at work 

 detaching and carrying aH the soft sea-weed it could collect to 

 one end of the aquarium, where it thus accumulated a large mass 

 of vegetation, which was afterwards destined to become a screen 

 and protection for its soft body. At the same time, and by the 

 same means, a clearing was made at the other end of the tank, in 

 which it had space for the evolutions which were subsequently 

 necessary for the extrication of its body. 



The Lobster remained in the peculiar rigid attitude I have 

 described, during the entire two days previous to the moult. On 

 the third day, a crack was observed along the membrane which 

 unites the dorsal surface of the first abdominal ring with the 

 carapace ; and when these parts became separated by about half an 

 inch, the bright-blue membrane of the new sheU being plainly 

 visible beneath, the operation of extricating the Abdomen com- 

 menced. By a strong vibratory action of the whole abdomen, 

 principally in a lateral direction, one segment was, at first, pro- 

 truded through the split ; and this was followed by an interval of 

 complete repose, during which the animal remained quite mo- 



