139 
A New Bet or TRILOBITES. 
By ANpREwW J. BIGNEY. 
It is conceded by those who have studied the rocks of Dearborn 
County that there are few sections in the country that are richer in in- 
vertebrate fossils. The Richmond formation is the outcropping stratum. 
In many places the streams have cut into the underlying Lorraine. During 
the past ten years the erosive action of the streams has been much greater 
than during any previous period of equal length of time. This is largely 
due to the removal of the forests from the hills and the cultivation of 
these lands for various crops. An examination of almost any stream shows 
the deep channels revealing new formations and rich beds of fossils, with 
interstratified clays. 
It was in such a place as this, one mile northeast of Moores Hill, that 
I discovered a small bed of Trilobites of the species Calymene (species ?). 
The bed does not measure more than three feet by four. The rocks are 
about three inches in thickness. It is of compact limestone, composed en- 
tirely of the trilobites, most of which have been partly dissolved and re- 
crystallized. Enough of the trilobites remain to enable one to recognize 
them. Nowhere in this section have there been so many trilobites found in 
any one place. Usually they are very scattering. Twenty-five years ago 
many specimens were found in various parts of the county, but I have 
never learned of so rich a find as this. In the same stream and not far 
away there are a few specimens to be found. This must have been an 
isolated portion of the ancient sea, especially favorable for the growth and 
accumulation of the trilobites. 
