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NEAV YORK STATE MUSEUM 



of these three are not identified with certainty. Two species are 

 identified as Helderbergian forms — Pholidops ovata 

 Hall and Rhynchospira formosa Hall. Among the 

 species described as new Favosites corrugatus ap- 

 pears to be the same as F. niagarensis ? Hall (= F. h e 1 - 

 derbergiae var. praecedens Schuchert), a coral found 

 abundantly in the Oobleskill. Another species Rhynchon- 

 ella agglomerata is the same as Rhynchonella? 

 litchfieldensis Schuchert. Both authors note a similarity 

 of the latter species to the Niagaran form Camarotoechia 

 n e g 1 e c t a Hall, to which species it was referred by the 

 writer. Of the other forms described Cladopora recti- 

 lineata Simpson, Monotrypa corrugata Weller, 

 and Wilsonia globosa Weller are found in the Wilbur 

 limestone. A study of the Leperditia of the Ulster county sec- 

 tion will undoubtedly show that it has a number of species 

 in common with the Decker Ferry formation. 



The evidence furnished by the study of the Decker Ferry fauna 

 shows that only the upper beds may be definitely correlated 

 with the Oobleskill limestone. Though Weller states that 

 [loo. cit. p.18] "the Decker Ferry formation, as well as the sub- 

 jacent beds down to the Medina formation, were probably con- 

 temporaneous with some portion or the whole of the Niagaran 

 formations of the interior," it can not longer be so considered 

 since it has been shown that in the section along Wheelock's 

 creek in Herkimer county the original " coralline " limestone is 

 separated from the Niagara by the Salina, the latter having a 

 thickness of more than 400 feet. It is evident that whatever 

 elements we find in the fauna of the Decker Ferry formation, 

 which are suggestive of Niagaran age, they must be looked on 

 as a late return of Niagaran species. The fact that the Decker 

 Ferry formation was, in part, deposited in a basin distinct from 

 that in the interior accounts for variations in the faunas of the 

 stratigraphically equivalent beds in central New York. 



Schuchert 1 includes all of the Decker Ferry formations under 

 the term Manlius and Weller states that the Oobleskill at Ron- 



1 Am. Geol. Mar. 1903. p. 174. 



