Page:The Habitat of the Eurypterida.djvu/25

 "The species common to both are Dolichopterus macrochirus and Pterygotus cobbi, both of which are quite rare, while the predominant species in both places are unlike. It is not believed that these differences necessarily express distinct stratigraphic horizons, as both lie near the top of the waterlime succession, but rather indicate original regional separation into distinct lagoons or pools . . . . which we may assume to have been synchronous. There is, in the face of the difference suggested, a certain degree of approximation in the two expressed by such vicarious species as E. remipes and E. lacustris, P. macrophthalmus and P. bufaloensis, which may well mean distinctions due to geographic isolation. The Herkimer pool is well restricted and its faunule cannot be traced very far towards the west; the Buffalo E. lacustris, however, appears alone as far east as Union Springs, Cayuga County, and as far west as Bertie, Ontario. Another difference in these faunas is the preponderating great size of all the species in the Buffalo pool, and, by contrast, the small size of and abundant young among the Herkimer county species;. . . . That the smaller creatures lived in conditions of shallower water is evinced by the sun-dried and cracked rock surfaces of their matrix, while such evidences are wanting in the Buffalo pool. . . ." (39, 92). Eurypterus remipes, one of the common forms in the Herkimer pool, is also obtained from the Rondout waterlime above the Cobleskill at Seneca Falls, Seneca county, New York.

The Manlius limestone of uppermost Monroan age has yielded fragments of Eurypterus microphthalmus from various localities in New York and also from Ohio. The type, a single cephalon, came from a loose boulder near Cazenovia, Madison county, New York, containing also fragments of Spirifer vanuxemi from which the age of the boulder was determined. One nearly entire specimen was found in the drift of Onondaga Valley, near Syracuse, New York. Of the number of carapaces now in the New York State Museum, one was collected "in the town of Litchfield in Manlius limestone, not less than 100 feet above the Eurypterus horizon in the Bertie waterlime" (39, 194). Professor Whitfield's type of E. eriensis (now regarded by Clarke and Ruedemann to be the same as E. microphthalmus Hall) came from the hydraulic limestones, the Put-in-Bay dolomite, of Beach Point, Put-in-Bay Island, Lake Erie, Ohio.

There is one more Siluric fauna to be noted and that is the one in the Kokomo waterlime of Indiana. Clarke and Ruedemann, following Schuchert correlate the Kokomo with the Noblesville of