Page:The Habitat of the Eurypterida.djvu/20

 grey or chocolate brown, bituminous dolomites which at some localities include bituminous shales," and to which Williams has given the name Eramosa beds (303, 1).

The bituminous nature of the dolomites and intercalated shales is indicative of near-shore conditions, and since these succeed the more purely marine facies of the typical Lockport, a shoaling or withdrawal of the sea, with a greater dominance of terrestrial sedimentation, is implied. The fauna is confined within some six inches of the bituminous shales and though fragments of a dozen or more species, including one eurypterid, have been found in abundance, not even generic identifications could be made with certainty. Williams gives the following list (303, 3):
 * Eusarcus logani Williams
 * Monomorella cf. orbicularis Billings
 * Orthis ? near tenuidens Hall
 * Spirifer radiatus Sowerby ?
 * Anoplotheca ? sp.
 * Lichenalia concentrica Hall
 * Orbiculoidea subplana (Hall)
 * Camarotoechia whitei (Hall)?
 * Whitfieldella nitida Hall?
 * Meristina ? sp.
 * Conularia niagarensis Hall?
 * Conularia sp.

The Lower Siluric occurrences, thus, are in formations containing undoubted and abundant marine faunas, but the eurypterids are represented either by fragments, or, in the case of the Guelph specimen, by a single though nearly perfect individual.

A recent discovery of considerable interest is the finding by Professor Van Ingen of Princeton University, of eurypterid remans in what appears to be the Tuscarora and associated beds of Swatara Gap, Lebanon County, Pennsylvania (39, 418, 419). In beds carrying Arthrophycus harlani ? he found: Another bed labeled 182 B 23 has afforded a carapace not
 * 1) Eurypterus maria. Large and small carapaces.
 * 2) Dolichopterus cf. otisius. Medium sized carapace.
 * 3) Stylonurus myops. Large and small carapaces.
 * 4) Hughmilleria shawangunk. Large carapace.
 * 5) Pterygotus cf. globiceps. Small carapace.
 * 6) Swimming leg of a Pterygotus or Hughmilleria.