96 



EECEEATIVE SCIENCE. 



A TRAVELLING OYSTEE-BED. 



Thkbe is, pertapg, no group of animals re- 

 specting which persons in general take less 

 interest than that which comprehends the 

 Crustaceans, or, in other words, crabs, lobsters, 

 and the like, some of which are continually 

 presented to our notice as delicacies for the 

 table. When, indeed, the lobster, the crab, 

 or the crayfish are dressed and served up, 

 then attention is paid to them, and their 

 freshness and flavour are feelingly commented 

 upon ; but here the matter ends. And yet 

 the history of the Crustacea, from those of 



microscopic size, which give luminosity to 

 the ocean, to the spine-armed giants of the 

 •waters, is replete with marvels. Manifold 

 are the changes which many undergo from 

 the egg to maturity ; strange are the habits of 

 others. Some are terrestrial, at least during 

 a greater portion of the year ; others semi- 

 arboreal, climbing trees in quest of fruit ; 

 others take up their abode in the shells of 

 sea-snails, having probably devoured the legi- 

 timate owner ; while others live amidst tan- 

 gled sea-weed, through the masses of which 

 they wend their way with incredible address. 



Many tenant the deep clear water, amidst 

 rocks and submerged ravines or glens ; and 

 not a few roam along the margin of the shore. 

 Largely might we dilate upon this part of 

 the subject, and largely upon singularities 

 of organization, but we must here pull in the 

 reins, our present design being merely to 

 offer a few observations on the specimen here 

 figured— ^it is an oyster-bearing crab. 



Among all the crustaceans, microscopic 

 or gigantic, the mode of growth is eff'ected 

 in a very peculiar manner, evincing most 

 strikingly the wisdom of God in creation. 



We know that crabs and lobsters, and 

 all their tribe, grow. We see them of dif- 

 ferent sizes, and according to their mag- 

 nitude {cceteris paribus) does the fishmonger 

 charge the purchaser for them. 



Now, if we look at a crab or a lobster (and 

 the observation applies to the totality of the 

 group, from the minutest to the most pon- 

 derous), we perceive at once that, like an 

 armed knight of old, it is cased in complete 

 and unyielding plates of mail, confining the 

 limbs and body within definite limits, and 

 which, like the rigid shoe on the foot of a 

 Chinese lady, seem to preclude the idea of fur- 

 ther increase ; yet grow it does, and the crab, 

 before the year is over, if left to itself in its 

 native waters, will be found to have increased 

 surprisingly, perhaps by a third or quarter of 

 its original bulk and dimensions. 



Here, then, are we led to inquire into the 

 modus operandi by which this increase of 

 bulk is efiected. 



It is by a process termed exuviation, that 

 is, a moulting of the old shell, that liberty is 

 given for this now naked animal to expand in 

 all its proportions. Not only are the plates of 

 the body thrown ofi", as well as those of the 

 limbs, but the sheathing of the antenna;, fine 

 as they may be, even of the spines and hair- 



