I know of no work on Natural History that speaks of the Hermit-Crabs (_Anomoura_) casting their shells, and on this account I have given some attention to them. These animals being so common, I kept by me at least a dozen specimens for the purpose of observing some of them, if possible, in the act of exuviation. The result of my labours has not been so satisfactory as I could wish, from my not having been able to collect any 'sets' of exuviæ. I cannot, therefore, speak with certainty as to the frequency of this phenomena. By this time my readers will know that the tail of the Hermit-Crab is very tender and fleshy, being covered merely with an extremely delicate membraneous skin, while the carapace, claws, and antennæ of the animal are protected by a hard crust, similar to the Lobster, Cray-fish, &c. From this peculiar formation of the crab, I was not at all surprised to find, on several occasions, the upper part of its body alone cast off, and therefore came to the very natural conclusion, that as the tail was soft, it would grow and increase in proportion to the other parts of the animal, without ever needing the skin to be changed. Each morning and evening during the time my experiments were being conducted, I examined all the tanks attentively, to see whether an exuvium had been cast. If visible, the object was picked out and gummed in a box, and a date placed above it for future reference. After having performed an operation of this kind one afternoon in October 1858, I saw a Hermit-Crab (who had cast his shell on the previous day) hurriedly leave his testaceous dwelling, then scrape away at his tail, and after a moment's interval, leap into his old seat again. On inspection, I found to my surprise _that he had actually_ _slipped off the skin of his tail_![7] much in the same fashion as we would draw off a well-fitting glove. Here was a strange and unexpected discovery. [7] The fact of the exuvium of the Hermit-Crab being cast off in two pieces, and at different periods, I have since confirmed 'many a time, and oft.' On submitting the exuvium to the microscope, we find that the covering of the false feet, and the cilia attached to the same, all remained fixed in their natural position to the tail-piece. Although in several cases I have had no difficulty in discovering the rejected cuticle of the tail, at other times it has eluded my search. The cause of this I cannot explain. It may be that the animal, adopting the habits of the toad, swallows a portion of its exuviæ as soon as cast. On two occasions I found the slough of the body and claws of a crab, and waited patiently for several days, without success, expecting to get the tail portion. Growing impatient, it occurred to me that it would be a curious experiment to try and draw off the exuvium with my fingers. This was easy to talk about, but difficult to perform.