UNIVALVES. 183 
** Armaments, whose thunders strike the walls 
Of rock-built cities, bidding nations quake,” 
were liable to be destroyed by the bite of an insigni- 
ficant reptile, in order to teach mankind the weakness 
of their boasted strength. But mark the protect- 
ing care of Providence. The destructive operations 
of these insidious animals are in a great degree 
obviated, by the singular fact of their generally per- 
forating the wood in the direction of the grain. 
The fossil cases of the Teredines, are termed Tubuli 
Fossiles. They are found buried in the earth, and 
vary considerably in appearance. Some are dis- 
covered, in a more or less perfect state, in strata of 
earth or stone; others, which are immersed in masses 
of the Ludus Helmontii, or Septarie, constitute 
a kind of pipe stone; but the most beautiful of 
this description, are broken fragments of vessels, or 
marine posts, which have been originally pierced by 
Teredines, and afterwards petrified, with the cases, 
or tubuli of the worms, remaining in them. 
Elegant specimens of these are brought from the 
shores of Sheppy, and the London and Richmond 
clay-pits. 
Teredines abound in the richest provinces of 
Holland, where the inhabitants behold the frightful 
spectacle of their great rivers held up by dikes at 
the height of twenty, or even thirty feet above the 
