Review of the New York Geological Reports. 315 



It is much to be regretted that so few figures of the Niagara 

 corals are given in the Report, since the organic remains of the 

 western strata referable to the same geological epoch are almost 

 exclusively of this class, and figures of the New York species 

 would serve as excellent guides in settling some disputed points 

 of identity. We presume, however, that the forthcoming vol- 

 ume on palaeontology will supply this deficiency. 



The following is a list of the remaining fossils of the Niagara 

 group, taken from Hall's Report. 



Atrypa imbricata, A. (species undetermined), A. cuneata, A. 

 nitida, Orbicula 1 squamiformis, O. cori^ugata^ Lingula lamel- 

 lata^ Avicula emacerata, Euomphalus hemisphericus, Corniilites 

 arcuatus, Orthoceras annulatiim 7 Conularia quadrisulcata. 



Hypanthocrinites ccelatus, H. dccorus, Marsupiocrinites ? dac- 

 tylus. 



Platynotus Boltoni, Asaphus Coryphceus. 



Catenipora escharoides, C. agglomerata, Porites ? 



Gorgonia 7 retiformis^ Gorgonia 7 7 Isis 7 



But little doubt is entertained that the Niagara shale and lime- 

 stone are equivalent to the lower members of the upper Silurian 

 rocks of England. Hall, speaking in general terms of the corals 

 and other fossils of the calcareous bands in the upper part of the 

 Niagara shale, has the following remark. " The perfect simi- 

 larity of these with specimens from Dudley in England, together 

 with the identity of many of the organic forms, renders the con- 

 clusion unavoidable that the two are formations of the same 

 age." The lithological character of these New York and Silu- 

 rian strata is wonderfully alike. 



The coralline beds of the magnesian limestone formation of 

 Iowa and Wisconsin, as well as the coraUine beds of the falls 

 of the Ohio, will doubtless prove to be their western equivalents, 

 though the lithological resemblance is not so apparent. 



It is worthy of remark, " that the Wenlock limestone contains 

 some forms identical with those of the lower limestones of the 

 Helderberg division, which in New York are separated by the 

 Onondaga salt group, one thousand feet in thickness," yet, as 

 Hall suggests, " we can account for this apparent difference upon 

 the supposition that the latter formation does not exist in Eng- 

 land, and that the higher limestones come down upon the lower, 

 or equivalent of the Niagara, and the whole are recognized as one 

 formation." 



