Mr. P. H. Gosse on the Sloughing of the Spider-Crab. 211 



sion, and in the highest possible condition ; many of them loaded 

 with ovigerous vesicles. 



While in the act of securing the crab in my collecting-basket, 

 esteeming it only on account of the zoophytes it carried, I felt 

 the body fall away from the carapace, which hung for an instant 

 by the frontal part and then gently detached itself, with a 

 feeling to my fingers as if it had been torn away. On looking 

 at the crab I saw the new carapace perfectly formed and coloured^ 

 with no marks of injury where the slough had parted from it. 

 The whole of the limbs and the under parts still remained in- 

 vested with the old skin. 



My collecting-jar was not large enough to receive the animal, 

 which I was therefore compelled to bring home dry in the basket. 

 But I immediately covered it with sea- water on my arrival, after 

 it had been exposed about three-quarters of an hour. It was 

 very inert and seemed exhausted. My attention was taken up 

 with one of the zoophytes, which was new to me, and I did not 

 look again at the crab for about a quarter of an hour. It was 

 then in the very act of sloughing the remainder of its exuviae. 

 The whole of the limbs, the abdominal segments, the sternum, 

 with all the members of the mouth, came off entire, being con- 

 nected by the common integuments. 



When "I looked at it, the first thing that struck me was the 

 pulling of the legs out of their sheaths. The posterior ones 

 were freed first ; the anterior pairs were about half out, and the 

 animal pulled first at one, then at another, until they were quite 

 drawn out, as if from boots. The joints, as they came out, were 

 a great deal larger than the cases from which they proceeded. It 

 was evident that in this instance, neither were the shells split to 

 afford a lateral passage for the limbs, nor were the limbs reduced 

 to tenuity by emaciation. It seemed to me that the parts, which 

 had an almost jelly-like softness when extruded, were compressed 

 as they were drawn through the narrow orifices by the fluids 

 being forced back, these returning through their vessels, and 

 distending the liberated portion of the limb, as it was freed. 



The enlargement of the whole animal was as immediate and 

 imperceptible in its progress as that of a caterpillar in the act of 

 moulting. I measured some of the dimensions soon after the 

 completion of the process, and found them as follows : — 



In the slough. In the crab. 

 Length of the carapace to the tip of frontal spines ... 3|^ in. 4f in. 



Width of the carapace at the lateral spines 3-]-^ „ ^i >» 



Diameter of thigh of first true leg x\ „ -^^ „ 



The claws of the anterior feet, and the black horny points of 



14* 



