Page:The Habitat of the Eurypterida.djvu/209

Rh at different horizons, and continuous widespread faunas are entirely wanting.

(1) As illustrations of the scattered occurrence of single specimens of eurypterids may be mentioned: Strabops thacheri in the Upper Cambric, Echinognathus clevelandi from the Utica, Eurypterus prominens from the Clinton, Eurypterus boylei from the Guelph, Eurypterus microphthalmus from the Manlius, and Eurypterus douvillei from the Rothliegende.

(2) As an instance of the same species occurring in places many miles apart, Eurypterus remipes may be cited. This species has been found in Waterville, Oneida County, N. Y. in great numbers; at Jerusalem or Wheelock's Hill, Herkimer County; to the northeast (near Cedarville) and west (Paris Hill) of Jerusalem Hill, near Oriskany; at Cayuga Junction, Cayuga County; and possibly at Buffalo. In all of these localities it has been found in the uppermost part of the Bertie, but at Seneca Falls, Seneca County, specimens have been found in the Rondout Waterlime (which may be possibly of the same age as the Bertie). There are several cases of closely related species occurring in localities separated often by great distances. One example that may be cited is that of Eurypterus lacustris, E. remipes and E. fischeri. For a long time the Baltic form (E. fischeri) was identified with E. remipes and it was not until Eichwald pointed out the differences in surface sculpturing and certain other characteristics, that the species was made distinct. Clarke and Ruedemann conclude their discussion of the comparion of these two species by saying that, "Altogether, the differences are so small that Schmidt's suggestion that they are but geographical varieties is fully supported" (39, 172). They add, further, that E. remipes and E. lacustris "are more closely related to each other than either of them to E. fischeri, indicating that they had but lately separated. Their differences rest mainly in the shape of the carapace and they are duplicated by those between E. fischeri and E. laticeps, two forms associated in the same [Baltic] rocks" (39, 172). Eurypterus fischeri has been found in Oesel and in Podolia.

(3) The data on the distribution have brought out clearly the fact that at no geological horizon is there a widespread or continuous eurypterid fauna indicating passageways of migration. Even in the Upper Siluric, which marks the acme in all respects for the eurypterids, the fauna does not show that universality which would be expected of denizens of the sea or of organisms whose immediate