8» 
THE GEOLOGIST. 
of the ancient predatory tribes. In the Mansfeld slates thou- 
sands of iish, with scarce a scale displaced, may still (apparently) 
present in their contorted frames, the agonies in which their 
existences were terminated. The tree or plant may be yet erect — 
or its prostrate stem, or broken gnarly boughs may be eaten 
through and through by the sea-wood-worm (teredo)* — the one 
grew where it stands, the other, drifted over the wide ocean, speaks 
in its riddled substance, in sUent eloquence of its wanderings. 
He who carefully notes the position of the fossU, who records 
faithfully where it was found and how, is no mere collector; 
depend upon it he knows something still more of the value of a 
fossil. 
One cannot begin everywhere at once, so something must be taken 
for granted. Among those things I must put upon the faith of the 
reader, are first, that this world is of very great antiquity ; millions, 
many thousands of millions — even myriads — of years old. And 
yet that it shall not be altogether on trust, we will draw again on 
one or two common fossils for just evidence enough to show that 
the strata are not of diluvial origin, but that time was taken to 
form them. 
What do we see on our own shores where dead shells 
lie exposed on the surface of the mud ? that worms (serpulffi,) 
zoophytes, sponges, algae, and parasites of all descriptions encrust 
them with a little community of life. 
XiGB 8. Valve of Foiail oyster from the white chalk (of Dorer,) with jomg oyiter attaehed to the 
internal surface. 
* The " ship-worm " of the present seas. 
