PALEONTOLOGY. 433 



No. 2, a thin layer of limestone, four to six inches thick densely 

 filled with teeth, plates and bones of fishes, locally known as the "Bone- 

 bed." 



No. 3, about thirty feet of thin-bedded shaly limestone, the "Dela- 

 ware bed" of Prof. Orton. The upper part of this is supposed to repre- 

 sent the beds of similar character at Delaware, Ohio, which contain the 

 large fish-remains. 



No. 4,' about fifteen feet of bluish, somewhat marly shales, the"01en- 

 tangy shales" of N. H. Winchell. This is followed above by the Huron 

 shales, the supposed equivalents of the Genesee slates and Portage shales 

 of New York. 



Near the lower part of No. 3, only a few feet above the "Bone-bed," 

 occurs the dark brown shale in question, with the peculiar fossils, which 

 I have no hesitation in pronouncing the equivalent of the Marcellus 

 s hales of New York. Admitting this — and there certainly appears to be 

 no alternative — the rocks found above this limit should represent the 

 Hamilton group of the New York system ; and we ought to find some 

 fossils here, characteristic of that formation, which would not pass below 

 this line. To ascertain if this was so, 1 requested Mr. Edward Hyatt, 

 who has collected carefully the fossils around Columbus, to furnish me a 

 list 1 of the species known, with their horizons indicated; and also re- 

 quested the use of specimens of species not known to occur below the 

 horizon of the " Bone-bed," that being the most easily recognized limit, 

 and the one most generally studied in connection with the vertical dis- 

 tribution. Contrary to my expectations, the species yet known not to 

 pass below the "Bone-bed" are very few. These, with the exception of 

 the Tentaculites scalariformis , have been illustrated on Plate III, and are, 

 with two exceptions, known Marcellus and Hamilton types, one being a 

 new species, and the other (Spirifera Maia Bill.), occurring in the Upper 

 Helderberg limestone in Canada. The examination of the upper layers 

 for characteristic fossils was not carried far enough to make it perfect, 

 owing to Mr. Hyatt's absence from Columbus ; but the few forms found 

 above these bituminous layers will readily be recognized as characteristic 

 of the Hamilton group, and warrant one in considering the Black shales 

 and other beds coming above these thin limestones in central Ohio, as 

 equivalent to the Genesee slates and succeeding formations of New 



York. 2 



The following lists, prepared by E. and H. Hyatt, of Columbus, 

 Ohio, are from the limestones within twenty-four miles of that place. 

 Those of the first list are from below the horizon of the " Bone-bed," 

 and the next from above ; Strophomena ? homboidalis being the , only 

 species fully recognized from both horizons. All species have been col- 

 lected by them from known horizons, or have been seen from the beds 



by myself. 



1 Names given by Mr. Hyatt, which I cannot verify.— R. P. W. 

 2 These lists will be found appended at the end of the present article. 



28 G. O. 



