228 SCIENCE SKETCHES. 
So the old Favosites died, or ran away, or were 
walled up by the younger ones, and new ones 
filled their places, and the colony thrived for a 
long while, until it had accumulated a large stock 
of lime. 
But one day there came a freshet in the Meno- 
monee River, or in some other river, and piles of 
dirt and sand and mud were brought down, and all 
the little Favosites’ mouths were filled with it. This 
they did not like, and so they died; but we know 
that the rock-house they were building was not 
spoiled, for we have it here. But it was tumbled 
about a good deal in the dirt, and the rolling peb- 
bles knocked the corners off, and the mud worked 
into the cracks, and its beautiful color was de- 
stroyed. There it lay in the mud for ages, till the 
earth gave a great long heave that raised Wisconsin 
out of the ocean, and the mud around our little 
Favosites packed and dried into hard rock and 
closed it in. So it became part of the dry land, 
and lay embedded in the rocks for centuries and 
centuries, while the old-fashioned ferns grew above 
it, and whispered to it strange stories of what was 
going on above ground in the land where things 
were living. 
Then the time of the first-fishes came, and the 
other animals looked in wonder at them, as the 
Indians looked on Columbus. Some of them were 
like the little gar-pike of our river here, only 
much larger, — big as a stove-pipe, and with a crust 
as hard as a turtle’s. Then there were sharks, of 
strange forms, and some of them had teeth like 
bowie-knives, with tempers to match. And the 
