UNIVALVES. 185 
ing to each its station, and so admirably adjusting 
the mighty whole, that every particle of matter, and 
every living thing that creeps, or moves, upon the 
surface of the earth, is formed in subserviency to 
the general good. Indeed in various instances, the 
lower we descend in the scale of creation, the more 
obvious are the uses, and the more extraordinary the 
instincts, of many of the creatures which compose it. 
Providence has mercifully appointed that such should 
be the case; and the reason is obvious: for, if the 
destructive, and congregating propensities of the 
Whale, and Shark, were similar to those of the Teredo 
navalis, the skill and ingenuity of man, would be 
almost inadequate to counteract the machinations of 
such sagacious and persevering foes. 
Sea-Worms, though apparently so pernicious to 
our shipping, have the same office assigned them in 
the water, as Z’ermites have on land. You are perhaps 
aware that these extraordinary insects, which to a 
easual observer appear solely occupied in spreading 
terror and destruction wherever they advance, are 
nevertheless of infinite importance to the well-being 
of mankind in the sultry regions of the globe. They 
consume decaying vegetable substances, of various 
kinds; they also resemble common flies in their 
general operations ; those indefatigable little labourers, 
the pioneers of cleanliness and order, which conti- 
