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their properties only, be, in a great meafure, able to 
range them in the rank, which they were designed to 
hold by Divine Providence. 
In order to this, let us fee firft what are thofe ani- 
mals, which we are acquainted with, who certainly 
fabricate their dwelling-places, as they grow for them- 
felves ; and what the common or ufual advantages 
are, which they are in general obferv’d to be endow’d 
with ; which will be beft done, by taking a near 
view of them. All the teftaceous tribe, whether of 
land or water, and whatever their forms be, may be 
faid to produce their own habitations, but not to fa- 
bricate them. For we muft obferve, there are but 
two modes, by which thefe kinds of animals are fur- 
nifhed with them; the one by fecretion from them- 
felves, and thefe neceftarily grow with them; the 
other by a defign’d apportion of parts of the ani- 
mals themfelves. Now, in the firft cafe, there is a 
neceftity for a juft proportion between the animal 
itfelf, and the fhelly matter fecreted from it. It muft 
be large enough, and have liability and ftrength in 
proportion to the matter which it fecretes, and is to 
move about with ; and it will appear, that this is- 
the general rule thro’ nature : Or, if it be an immove- 
able body, the creature ought certainly to be allow’d 
fo much fignificancy and ftrength, as would, on the 
one hand, feem neceffary for the fecretion of fo 
much matter, as was fufficient to conftitute that 
body ; or, on the other, to be capable, by its own 
proper adtion, of gathering together the matter, and 
building up the ftrudture. Where this is wanting, I, 
for my own part, would be far from haftily con- 
cluding fuch work to be the fabrication of fuch 
S f f 2 ' feeding 
