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Carbonic (Mississippian) 
WAVERLY BEDS 
Eurypterus approximatus Hall & Clarke. Warren, Warren co., Pennsylvania 
PRODUCTIVE COAL MEASURES 
Eurypterus (Anthraconectes) mazonensis Meek & Worthen. Mazon creek, 
Indiana | | 
Ek. (A.) mansfieldi C. EF. Hall. Beaver county, Pennsylvania 
E. (A.) pennsylvanicus C. E. Hall. Venango county, Pennsylvania 
E. ? potens ¥. Hall. Pennsylvania 
EK. (A.) stylus ¥. Hall. Beaver county, Pennsylvania 
B Biologic facies of the eurypterid faunas 
It is not necessary for us to discuss here the Algonkian' and Cambric 
occurrences, further than to mention that the Cambric species which is a 
true eurypterid, conclusively demonstrates the great age of the merostomes 
and their early existence in truly marine beds.’ 
The earliest appearance of the eurypterids in profusion is in the Lower 
Siluric Frankfort shale of Schenectady and Schoharie counties, N. Y., 
lately discovered. Here at least 11 species, at present referred to the 
genera Eurypterus, Dolichopterus, Stylonurus, Eusarcus, Hughmilleria and 
Pterygotus, have been found to range through the eastern littoral marine 
development of the formation. 
The earliest appearance of the characteristic biologic facies of the 
Eurypterida in America is that in the waterlime of Kokomo, Indiana 
which contains four species of the order. Kindle [1904] has distinguished 
two stratigraphic horizons in the Niagaran of Indiana, which correspond 
to the Lockport and Guelph formations of New York respectively, and 
‘The Algonkian Beltina is referred to in the Appendix. 
?The Potosi limestone which has furnished this eurypterid contains, according 
to Beecher, an abundant and characteristic marine Cambric fauna [Amer. Jour. Sci. 
Igor: 362]. 
