406 New York State Museum 



Paleoneilo emarginata, Nuculites triqueter, Panenka re- 

 tusa etc. ; gastropods as Straparollus Jiccalc, Carinaropsis 

 ithagenia, Bellerophon patulus etc. ; cephalopods as Ortho- 

 ceras leander, Spyroceras pertextum, Gomphoceras tumi- 

 dum, Gephyroceras perlatum; crustaceans as Rhinocaris 

 capsella, and the trilobites Phacops rana and Homalono- 

 tus (Dipleura) dekayi. 



The Chemung beds (Hall '39) were named from ex- 

 posures in Chemung valley in the county of that name. 

 In western New York the Chemung formation overlies 

 the typical Portage beds, in central New York the Ithaca 

 beds, farther east the Oneonta beds. In the eastern sec- 

 tion through to Pennsylvania the fauna occurs sparsely 

 and the formation becomes involved with the red beds of 

 the Catskill formation which in the east overlies the One- 

 onta red beds and is the nonmarine equivalent of the ma- 

 rine Chemung beds to the west, representing Mississip- 

 pian time in its upper portion. In the east the Chemung 

 beds are undivided. In central New York this formation 

 has been divided into the Cayuta shale member and the 

 Wellsburg sandstone member with the Fall Creek con- 

 glomerate lentil at the top (Williams '06). The Cayuta 

 shale member was named from exposures along Cayuta 

 creek, in Schuyler, Chemung and Tioga counties. It has 

 a thickness of 600 feet and carries the typical Chemung 

 fauna. The Wellsburg sandstone above, typically ex- 

 posed in the vicinity of Wellsburg, Chemung county, has 

 a thickness between 400 and 800 feet and near the top 

 contains a ten-foot lentil of conglomerate, the Fall Creek 

 conglomerate. In western New York the Chemung for- 

 mation has been divided into a number of members and 

 the Dunkirk shale and Laona sandstone previously in- 



