Exuviation of the Common Crab. 343 



colour above was red, beneath a pale yellow, the flap purplish ; the 

 bristles on the legs fully formed, but soft, which is the more worthy 

 of notice, as I have seen the Porcellana platycheles, in which villo- 

 sity forms a conspicuous character, entirely naked when just escap- 

 ed from the crust. On cutting open the legs and chelae, the bony 

 plates to which the muscles are attached, and which serve for ten- 

 dons, were found as soft as wet parchment, and towards the extreme 

 joints, could not be distinguished with certainty. On breaking off 

 the largest chela at the joint where the animal is itself accustomed 

 to separate it when injured, the usual membrane formed towards 

 the body, and no discharge took place ; but a watery fluid proceed- 

 ed copiously from the surface towards the limb, which was thus soon 

 left empty, speedily becoming capable of being blown up with air 

 like a bladder. On proceeding to dissect the body a similar cir- 

 cumstance took place, the fluid running ofl* in so large a quantity, 

 that I regretted when too late, that I had not taken the precaution 

 to have measured it. In a few minutes, the body had so sunk into 

 one mass that I was unable to distinguish the separate parts. At 

 the lower and inner part of each joint of the chelae and legs, an 

 opening remained, in the form of a slit ; through which the flat cen- 

 tral bony plate, found in the empty crust, had been withdrawn ; 

 which opening of course must be closed when the shell is finally con- 

 solidated. 



It appears from close inspection, that the exuviae of a lobster con- 

 sists of the same parts as those of a crab ; the whole internal skele- 

 ton and external surface of the branchiae, with the osseous tendons 

 of the muscles, having been rejected. But they are more distinctly 

 ascertained in the latter species, from their greater firmness of tex- 

 ture ; and I may add also in reference to myself, that a desire to 

 preserve the specimen perfect, had in the former case prevented a 

 very minute examination of the internal structure. 



Having procured a crab that was beginning to show signs of a 

 commencement of the process of exuviation, I found the limbs shrunk 

 to three-fourths of what the shell could well contain ; the soft con- 

 tents of the points of the chelae being diminished much more than 

 the muscular structure. A greater diminution than this, however, 

 takes place before the process of deliverance is accomplished ; but 

 all the vigilance that I have exerted has not enabled me to see the 

 actual escape from the crust ; which is usually left in some void 

 place, often in a sandy basin, and, as several fishermen have inform- 

 ed me, always on its back ; as the living specimen I have describ- 

 ed is represented also to have been found in the store-pot. 



The newly extricated crab has at first strength enough to crawl 



