Page:The Habitat of the Eurypterida.djvu/124

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118
THE HABITAT OF THE EURYPTERIDA

or no eurypterid remains, but more marine organisms. That the Bertie eurypterids lived in the rivers is thus indicated, while their absence from the Rosendale could be explained by assuming that the present exposures of these rocks are in the more marine portion of the deposit. The relations are shown in the following diagrams (figs. 5 and 6).


6. THE KOKOMO WATERLIME

The Kokomo waterlime of Indiana is of very much the same character as the Bertie waterlime, showing the same thin laminations and fine texture. Throughout a limestone series forty feet thick thin waterlime layers occur and it is in these alone that the films of eurypterid

Fig. 5. Ideal N. W.-S. E. Cross Section from Buffalo, N. Y. to Tyrone, Pa., Showing Conditions During Bertie Time

Fig. 6. Generalized Cross-Section of the Same Region Showing Present Conditions due to Post-Bertie Deposition and Erosion

exoskeletons are found. In the pure limestones a brachiopod fauna occurs, but no eurypterids are present; while in the separating waterlime eurypterids and ceratiocarids, but no brachiopods are found. Foerste has made the following statements in regard to the occurrence: "At the McReynold or Interurban quarry, in the southwestern corner of Kokomo, there is a much thicker exposure of the upper or brachiopod horizon. No merostomata have been found here.

"South of the center of Kokomo within the town limits, there is a deep quarry, covering a considerable area, where merostromata are common at an elevation of 3 to 3 feet above the base of the quarry. This belongs to the lower thinly laminated part of the section, and the richly fossiliferous brachiopod beds appear to be absent" (Foerste, 67, 7).