Page:The Habitat of the Eurypterida.djvu/113

 Here we see that the Bertie follows upon the Camillus shales and gypsum, a part of which may belong to the undoubted Salina or Middle Siluric, but the upper part of which certainly belongs with the Bertie to the Upper Monroe, since it contains Leperditia scalaris. At Buffalo the Bertie is conformably succeeded by the Akron dolomite, an impure rock 7 or 8 feet thick, containing the Upper Monroe fauna sparingly distributed, and marking the return of normal marine conditions.

In areal distribution the typical Bertie is not a continuous formation, but is found well developed at only two localities; namely, in Erie and in Herkimer Counties, New York, where the sediments were deposited in what Clarke and Ruedemann have called the Buffalo and Herkimer "pools." These two pools or basins are considered to