Pi'i' Cent 



36 





o 



5 



3 



5 



29 





G4 





3 



5 



46 





3 



5 



j\[ai!Ylaxd Geological Survey 93 



Nuiii)>Hr 



Species possessing significance for correlation 28 



Occurring in New Yoric only in the Onondaga or earlier 



formations 10 



In Oriskany 1 



In Schoharie 1 



In Onondaga 18 



Occurring in New York only in the Marcellus or later 



formations 17 



In Marcellus 1 



In Marcellus and Hamilton 12 



In Genesee 1 



This table shows the clearly preponderating relationship of the fauna 

 as a whole to the Marcellus fauna of New York. 



The stratigraphic relations indicate no less clearly an age earlier than 

 the upper part, at least, of the Marcellus of New York. The i\Iarcellus 

 is characterized by Liorln/nchiis limitare, which may be considered its 

 guide fossil both in New York and Maryland. The beds containing this 

 species overlie the fauna under coiisideration in Maryland and the adjoin- 

 ing states, and also throughout the Appalachian region according to Kin- 

 dle. The constancy of this position indicates that tlie Onondaga fauna 

 of Maryland is older than the zone of Liorhynchus limitare.^ Litho- 

 logically the iissile dark shales found in some of the lower beds of this 

 member suggest the Marcellus while the other beds resemble the sliale of 

 the Hamilton. 



The foregoing facts show that these deposits were laid down in a basin 

 in which many Onondaga species were present, but after the advent of 

 many other forms restricted in New York to the Marcellus and Hamilton, 



^ Prosser reported L. limitare from the lower beds of the Romney in a 

 number of sections in Maryland, particularly at 21st Bridge and on the Wil- 

 liams Road S'j miles southeast of Cumberland. Kindle who has since 

 examined the same sections failed to find that species at the horizons indi- 

 cated by Prosser. 



Anoplotheca acutiplicata, which is thought by Kindle to be diagnostic of the 

 Onondaga, is also reported by Weller from the Newfoundland Grit and the 

 Monroe shales of New Jersey, both of which overlie the Onondaga limestone 

 (Pal. N. J., vol. lii, 1903, pp. 105, 106). It is associated in the Monroe shales 

 with Tropidoleptus carinatus. It is also reported by Prosser as occurring 

 rarely in the Hamilton of Maryland. 



