Page:The Habitat of the Eurypterida.djvu/99

 and a few very poorly-preserved, marine fossils, which last, by their very scarcity and by the evidences which they show of having been transported, argue more strongly for than against the extra-marine habitat of the well-preserved eurypterids and Ceratiocaris.

The application of the criteria for the recognition of the types of fossil faunas and habitats shows beyond any doubt that the eurypterids, so far as we now know, never lived in the sea or in any partially or wholly detached portion thereof; the only possible type of fauna to which the eurypterids could have belonged was that which dwelt in rivers, and this is nowhere more clearly shown than in the Siluric, which marked the acme in development and universality of distribution for the Eurypterida.

The formations which in America contain eurypterids in abundance are:
 * 1) The Belt Terrane.
 * 2) The Normanskill and Schenectady beds.
 * 3) The Shawangunk conglomerate.
 * 4) The Pittsford shale.
 * 5) The Bertie waterlime.
 * 6) The Kokomo waterlimes.

Those most prolific in Europe are:
 * 1) The Tarannon and Wenlock beds of southern Scotland.
 * 2) The waterlime beds of Oesel.
 * 3) The Siluric of the Austro-Russian border lands.
 * 4) The Ludlow of England and Ludlow and Lanarkian of Scotland.
 * 5) The Old Red Sandstone.

It is evident that the formations carrying only fragments or single individuals need not be considered if we can prove a uniform habitat from the formations carrying these merostomes in abundance. Nevertheless a brief summary of these is also given at the end of the chapter.

The Belt Terrane fauna is a large one made up of fragments which Clarke and Ruedemann have failed to identify as of merostome