212 Mr. P. H. Gosse on the Sloughing of the Spider-Crab. 



the ambulatory feet, were increased in size more than propor- 

 tionally, as were the abdominal foot-processes. 



The whole of the branchiae were represented in the most beau- 

 tiful order in the exuvise, with the crescentic flabellum laid over 

 each series perfectly in situ. They were enveloped in an ample 

 and most delicate mucous membrane, which was attached to the 

 margin of the crust all round, and was evidently the lining mem- 

 brane of the branchial cavities. The coats of the stomach, with 

 its minute teeth, were also there in the form of a membranous 

 bag, attached to the mouth by the lining of the oesophagus. 

 The coats of the antennae and of the eyes remained attached to 

 the carapace; and the glassy cornese of the latter were not 

 reversed. 



On opening a joint of one of the legs of the exuvise, I found 

 the thin shelly plates that aiford attachment to the muscles still 

 in situ. 



I was struck with the beautifully regular though minute ser- 

 rature of the opposing edges of the claws in the renewed ani- 

 mal, the teeth closing accurately into the intervals of the oppo- 

 site series when appressed. Scarcely a trace of any such struc- 

 ture could be discerned in the slough ; the teeth having been 

 probably worn smooth by use. 



I did not see any of the struggling that is sometimes spoken 

 of; it seemed to be a very easy and simple matter. The new 

 integuments were perfected, though soft, before the old were 

 thrown off, and the immediate cause of the separation of the 

 crust appears to me, the sudden growth of the animal within, 

 forcing asunder the upper and lower crusts at the posterior 

 margin : then the pulling out of the limbs presents no more 

 difficulty than what depends on the enfeebled condition of the 

 muscular energy. 



The great claws of the common crab and of the lobster, of 

 course, suggest a more difficult operation. But the congruity 

 seen in the operations of nature makes it unlikely that one mode 

 of procedure would obtain in these and another in a species so 

 affined as the Spider-Crab. Hence, I presume that even these 

 members, bulky as they are, are drawn through their narrow 

 joints, not by being emaciated, but simply by being softened, and 

 by their fluids being displaced in detail. 



Ilfracombe, Devon, August 14, 1852. 



