90 . A CENTUEY OF SCIENCE 



Sweden. The Black Kiver and Trenton hold the position 

 of the Orthoceras limestones of Sweden and Russia, 

 while the Utica and Lorraine are represented by the 

 Graptolite beds of the same countries. Both correlations 

 are in partial error. He unites the Chazy, Birdseye, and 

 Black Eiver in one series, and in another the Trenton, 

 Utica, and Lorraine. Of species common to Europe and 

 America he makes out seventeen. 



In the Upper Silurian system, the Oneida and 

 Shawangunk are taken out of the Champlain division, 

 and, with the Medina, are referred to the Silurian, along 

 with all of the Ontario division plus the Lower Helder- 

 berg. The Clinton is regarded as highest Caradoc or as 

 holding a stage between that and the Wenlock. The 

 Niagara group is held to be the exact equivalent of the 

 Wenlock, "while the five inferior groups of the Helder- 

 berg division represent the rocks of Ludlow." We now 

 know that these Helderberg formations are Lower Devo- 

 nian in age. De Verneuil unites in one series the 

 Waterlime, Pentamerus, Delthyris, Encrinal, and Upper 

 Pentamerus. Of identical species there are forty com- 

 mon to Europe and America. 



The Devonian system De Verneuil begins, "after 

 much hesitation," with the Oriskany and certainly with 

 the five upper members of HalPs Helderberg division, all 

 of the Erie and the Old Red Sandstone. He also adjusts 

 HalPs error by placing in the Devonian the Upper Cliff 

 limestone of Ohio and Indiana, regarded by the former 

 as Silurian. The Oriskany is correlated with the grau- 

 wackes of the Rhine, and the Onondaga or Corniferous 

 with the lower Eifelian. Cauda-galli, Schoharie, and 

 Onondaga are united in one series ; Marcellus, Hamilton, 

 Tully, and Genesee in another; and Portage and 

 Chemung in a third. Of species common to Europe and 

 America there are thirty-nine. 



The Waverly of Ohio and that near Louisville, Ken- 

 tucky, which Hall had called Chemung, De Verneuil cor- 

 rectly refers to the Carboniferous, but to this Hall does 

 not consent. De Verneuil points out that there are 

 thirty-one species in common between Europe and Amer- 

 ica. "And as to plants, the immense quantity of terres- 

 trial species identical on the two sides of the Atlantic, 



