COMMON LOBSTER AND SHORE CRAB. 33 



Not only the claws, but the parts of the mouth, the antennaB, and 

 the eyes, were all unsheathed ; and with the last tug the regenerate 

 Lobster plunged backwards, and entirely escaped, above and be- 

 hind the now empty shell — its former tenement. 



The operation, from first to last, occupied about twenty minutes, 

 and was performed entirely in view, in that part of the aquarium 

 wliich the Lobster had cleared of sea-weed. 



Immediately after emerging from the old shell, the Lobster, was 

 much deformed : there was a general elongation of the whole 

 animal ; but this was most remarkably the case with the claws, 

 which were quite drawn out of shape. During the few subsequent 

 hours, both the body and the claws became shorter and much 

 enlarged. This increase of size did not result from any unfolding 

 of membrane of the shell previously plicated, as no folds were ob- 

 servable immediately after the emergence of the animal, but from 

 a simple distension, apparently from the imbibition, either by 

 swallowing or by endosmosis, of considerable quantities of water. 

 The membrane of the new shell was perfectly soft, and of a bright-- 

 blue colour. At first the Lobster was shy and quite inactive^" 

 retiring to and remaining concealed among the accumulated sea- 

 weed ; but in a few hours it emerged from its retreat, and moved 

 freely about the aquarium. The membrane of the new shell re- 

 mained soft for some days, btit on the seventh it appeared to 

 have become perfectly calcified. ^ 



These are the details of the exuviation of the Lobster whose '^ 

 cast-off shell is before the Society. By a happy accident, the* 

 same observers had an opportunity of witnessing the sloughing 

 of another Lobster, in the month of November following. The 

 process was identically the same in every particular ; but it was 

 observed that the subsequent calcification of the shell did not take 

 place till after the lapse of about fourteen days, — a circumstance 

 probably dependent on a lower temperature and a less active 

 nutrition. These are, I believe, the only two instances in which 

 the exuviation of the Lobster has been actually witnessed ; but 

 there exist specimens of sloughs which are entirely in keeping 

 with this description. In the fish-house of the Zoological Society 

 of London there are two specimens which were cast in the tanks 

 there ; and in each there is the same traijsverse splitting of the 

 carapace from the abdomen, and the longitudinal splitting of the 

 carapace itself, without any other opening for tlie escape of tlie 

 animal. 



One or two general observations are suggested by the foregoing 



LINN. PROC. — ZOOLOGY. 3 



