Association of American Geologists and Naturalists. 155 



Our Primal series embraces the four great rocks between the base 

 of the Palseozoic strata and the base of the first limestone, the calcife- 

 rous sandstone of New York. Of these the prunal white sandstone, 

 would seem to be the only formation existing in New York, or accor- 

 ding to Owen, on the northwestern margin of the basin in the western 

 states. 



The Matinal series includes all the strata from the horizon of the 

 base of the calciferous sandstone, to that which marks the top of the 

 Hudson River slate in New York, and the top of the blue limestone of 

 the western states. This series in southwestern Virginia and East Ten- 

 nessee, embraces a thick and important middle group consisting of 

 three formations, not extending northeast of the New River, and only 

 imperfectly represented in some portions of the western states. 



The Levant series includes all the formations between the horizon 

 terminating the Matinal rocks and one running through the top of the 

 water lime formation of New York, the top of the non-fossiliferous 

 and " pitted rock" of Lake Huron, and through a plain low in the cliif 

 limestone of the western states. It takes in, therefore, the Medina, 

 Clinton, Niagara and Onondaga salt groups, and water lime of the New 

 York survey. 



The Fremedidial series embraces the strata between the top of the 

 mater lime and the top of the Oriskany sandstone of New York, and 

 includes, therefore, the Pentamerus and Catskill shaly limestones of 

 that State as its oldest formation, and the Oriskany Sandstone as its 

 newest ; and besides these, a middle formation not there seen but well 

 developed in Pennsylvania, with characteristic fossils. 



The Medidial series ranks in it all the strata between the top of the 

 Oriskany or Fremedidial sandstone and the Marcellus black slate of 

 New York, or the black bituminous slate of Ohio, Indiana, Kentucky 

 and Middle Tennessee. It, therefore, includes the Schoharie grit and 

 Onondaga and corniferous limestones of New York, and the upper 

 division of the cliff limestone of the west. 



The Postmedidial series embraces that very natural assemblage of 

 formations commencing with the black slate just named, and crossing 

 with the horizon which marks the base of the Catskill red sandstone. 

 It contains, therefore, for New York the Marcellus shades, the Hamil- 

 ton group, the Tully limestone, the Genesee slate, the Portage group 

 and the Chemung group, and for the west all the strata between the 

 top of the cliff limestone sind the bottom of the carboniferous lime- 

 stone. 



