There is one singular feature in the Crustacea which it may prove interesting to dwell a little upon. I allude to their power of living apparently without food, or at least without any other sustenance than is afforded by the animalculæ contained in the water in which they dwell. One accurate observer states that he kept a Cray-fish for a period of two years, during which time the only food the animal received was a few worms,--not more than fifty altogether. This statement I have often had ample means of verifying. Yet, on the other hand, strange to say, the crab is always on the hunt after tit-bits; and nothing seems to give him greater delight than a good morning meal, in the shape of a newly opened Mussel, Cockle, and above all--a Pholas. Let a youthful crustacean cast its shell, and rest assured, unless its companions have had their appetites appeased, they will endeavour to fall upon and devour the defenceless animal. This, to my chagrin and annoyance, I have known to occur repeatedly. When nothing else can be procured, not only the Lobster Crabs, but any Brachyurous Decapods who may be at hand, will set to work, and industriously pick off and eat the Acorn-Barnacles attached to any object within reach. These facts show that the asceticism of the crab is not voluntary, and that when opportunity occurs, he is as fond of a good dinner as are animals possessed of a higher degree of organization. It will be gratifying if other observers are able to verify the circumstance which I shall allude to hereafter, and which would seem to show that the _exuviation_ of crustacea is expedited by affording specimens an unlimited supply of food. 'The organs for pursuing, seizing, tearing, and comminuting the food of the Brachyurous Decapods,' says Professor Bell, 'are carried to a high degree of development; ... these appendages consist of six pairs, of which some are actual organs of mastication, as the mandibles or the true jaws, the foot jaws or pedipalps, generally serving to keep the food in contact with the former, whilst it is being broken up by them. 'The buccal orifice in the Brachyura occupies the interior face of the cephalic division of the body, and is bounded anteriorly by a crustaceous lamina of determinate form, which has been termed the upper lip, and posteriorly by another, termed the lower lip. The mandibles occupy the sides of the opening. After these, and external to them, are the first, and then the second pair of true jaws, followed by the three pairs of pedipalps or foot jaws, the last of which, when at rest, close the mouth, and include the whole of the preceding ones. In the Macroura the pedipalps are very different in their forms, and have the aspect of very simple feet.