GEOLOGIC DISTRIBUTION OF NORTH AMERICAN SPECIES OF EURYPTERIDS AT PRESENT KNOWN
a The Schenectady beds have been termed in this work the Schenectady facics of the Frankfort beds. They are now referred to the upper Trenton as a distinct unit [see p. 411.] b The Shawangunk grit includes the faunis here described from the Delaware Water Gap and Swatara Gap in Pennsylvania [see p. 417]. c Mr Charles Butts informs us that this specimen must have come from either the Chemung as he has limited it, or his Conewango (Devono-Carbonic) formation. d The horizon of this species is unknown. It probably came from below the Productive Coal Measures (Pennsylvanian).
