l:J9 



A New Bel of Trilobites. 



By Andrew J. Bigney. 



It is conceded by those who have studied the roclvs of Dearborn 

 County that there are few sections in the country that are richer in in- 

 vertebrate fossils. The Richmond formation is tlie outcropping stratum. 

 In many places the streams have cut into the underlying Lorraine. During 

 the past ten years the erosive action of the streams lias been much greater 

 than during any previous period of equal length of time. This is largely 

 due to the remo^^al of the forests from the hills and the cultivation of 

 these lauds for A'^arious crops. An examination of almost any stream shows 

 the deep channels revealing new formations and ricli 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?). 

 Tlie 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 aijd 

 ,7CC:i;mulation of the trilobites. 



