|The eurypterid genus, Waeringoopterus, is one of the most abundant and most geographically widespread of the eurypterids occurring in eastern North America. It appears abruptly in the Late Silurian stratigraphic se- quence within a zone near the middle of the Salina Group. It disappears just as abruptly. Leutze ( ) was the first to study the distribution of Waeringopterus. I have traced the Waeringopterus Biozone farther west- ward, through Western New York and into Ontario, Canada (see photo at right). Sedimentologically, the occurrence is similar to the well-known horizons within the Bertie Group, ie. Waeringopterus: 1) occurs mostly in WINDROWS where remains are often collected together on bedding planes, 2) SALT HOPPERS are usually present, 3) STROMATOLITES are often associated with remains.