PREBLE COUNTY. 415 



Tery circuitous channel through the limestone rock. Attention was 

 called to this interesting fact by the late Dr. Dunham, of Camden. 



The geology of Preble county, it is to be remembered, is identical in 

 its various elements with that of counties already treated at considerable 

 length. To these reports the reader is referred who desires a fuller 

 sketch of the history written in the formations that make up its geo- 

 logical scaile. 



As Preble county is the last one to be reported upon in the district, that 

 contains the Upper Silurian formations, no more appropriate place can be 

 found for the insertion of a list of the Niagara and Clinton fossils of Ohio. 

 The appended catalogue contains such a list, no fossil being entered in it 

 that has not been recognized or de«3ribed by one or other of the Paleon- 

 tologists of the Survey : 



FOSSILS OF THE CLINTON LIMESTONE. 

 CORALS AND BEYOZOANS. 



Astrocerium venustnm Hall. 



Diphyphyllum oespitoaum • ...Hall. 



Chaetetes — undetermined Bp. 



Clathropora Clintonensls H. and W. 



Favosites Niagarensis Hall. 



Halysites catenularia Linn. 



Lichenalia ooncentrica Hall. ? 



Eetepora angulata Hall. ? 



Streptelasma — undetermined sp. 



Stiotopora magna H. and W. 



MOLLUSCA. 



BBACHIOPODS. 



Atrj-pa nodostriata Hall. 



Merista — undetermined sp. 



OrtMs biforata Dalm. 



' ' circulus Hall. 



Streptoihynchus subplana Hall. 



Triplegia Ortoni :, Meek. 



Zygospira modesta Hall. 



LAMELLIBEANCHS OR BIVALVES. 



Ambonychia — undetermined ep. 



Cypricardites ferrugineum H. and W. 



OASTEROPODS OR UNIVALVES. 



Cyclonema bilix - Hall. 



Holopea — undetermined sp. 



