342 Exuviation of the Common Crab. 
As quickly as possible, and without injury, the living crab and its 
empty representative were brought to me : and the following is a 
description of the exuviae. 
The longest diameter of the carapace was 6f inches ; compass of 
the largest chela, and length of the flap or tail, severally 3f inches : 
the individual a female, or what is termed by fishermen a Bon Crab. 
The carapace was sound, except on its under surface, where in its 
ordinary state a curved line passes backward from the jaws to the 
hinder part of the body. When caught on the 30th this portion was 
observed by the fisherman to be loosened ; and now the portion in- 
cluded between this waved line and the sternal plate, was entirely 
separate and fallen inward. The sheaths of the antennae and palpi 
perfect ; one eye gone, the other remaining, with the transparent 
covering perfect, the stalk loosely attached ; the tail and all its ap- 
pendages perfect ; the sternal plate beginning to break across in the 
middle, leaving to each portion a pair of legs on each side ; but this 
not being a complete or natural separation, may have been produ- 
ced by the weight of the limbs alone, or the efforts of the animal. 
The chelae and legs perfect in all their attachments, the membranes 
unbroken ; and the flat bones which occupy the middle of the muscles 
and serve them for tendons or points of attachment for motion, were un- 
injured and fastened to each joint, their distant extremities hang- 
ing loosely in the cavity of the case of the limb. The coverings of 
the branchiae were perfect to their minutest extremities ; and beside 
the internal coat of the stomach, the whole internal skeleton of the 
animal was thrown off without fracture or displacement : including 
the two motive bones or levers that pass through the middle of the 
body from the jaws, to be attached to the internal dorsal aspect of 
the carapace : where formerly attached, however, to the carapace they 
hung loose. The curious bony articulations of the grinding appa- 
ratus of the stomach, which renders the digestion of these Crustaceans 
analogous to the rumination of quadrupeds, together with the dou- 
ble crustaceous body (perhaps gland) at the pyloric orifice, and the 
whole of the bony crusts or chambers that receive the muscles which 
move the legs, were disengaged without displacement. 
The living representative of this wonderful skeleton measured 7i 
inches in its longest diameter, the compass of the largest chela, and 
length of the flap or tail, 4 inches ; the weight 24^ ounces, being 
5^ ounces less than an ordinary crab of the same dimensions, weigh- 
ed with it for comparison. It was plump, having much the appear- 
ance of a lump of dough enclosed in a membrane ; and it was also 
equally soft, with scarcely more power of motion ; appearing sensi- 
tive only when pressed on the under surface of the carapace. The 
