9X8 PALAEONTOLOGY OF NEW- YORK. 



• 



In the upper part of the Chemung group, and sometimes apparently 

 near the summit of the formation, there is a grayish or ferruginous con- 

 glomerate, often charged with fossil shells, among which there are usually 

 few Brachiopoda ; and in some localities the general aspect of the fauna 

 is more nearly like that of the Waverly sandstone of Ohio, some of the 

 species being apparently identical with those of that formation and the 

 western extension of the same. I have, however, detected in this con- 

 glomerate casts of Spirifera mesacostalis and S. verneuili = S. disjunda, as 

 well as other forms which show its intimate relation with the Chemung 

 group. 



These are the beds which I have heretofore indicated as those which 

 may become expanded in their western extension, and constitute in part 

 the fossiliferous sandstones and shales of Eastern Ohio ; while the Portage 

 and Lower Chemung beds, which do physically extend into that part of 

 Ohio, are less fossiliferous than in New- York, and their presence has 

 been overlooked by some observers. At the same time, there is a dis- 

 position not only to claim for the higher portions a distinct place in the 

 series, but to refer these beds to a distinct system. By whatever name, 

 however, they may be termed, they apparently constitute part of the great 

 group of argillaceous and ai-enaceous shales and sandstones which began 

 their deposition with the Marcellus shale, and terminate with the red 

 shales and sandstones of Pennsylvania, or at the base of the conglome- 

 rate of the Coal measures, as that formation exists on the borders of 

 southern New- York and the adjacent counties on the south and west*. 



• I had intended, before the completion of the volume upon the Brachiopoda, to have made personal 

 investigations to determine more accurately the relations of these formations ; but have been for two 

 jears prevented from accomplishing anj field work of importance. 



