No. 4.] HUNT — ON CAMBRIAN AND SILURIAN. 419 



(and Middle) Cambrian of Sedgwick. These conclusions were 

 set forth by him in 1842, in his report on the Geology of the 

 Northern District of New York [page 162]. See also his Agricul- 

 ture of New York [I, 49] the fifth chapter of which, " On the 

 Taconic system," was also published separately in 1844 ; when the 

 presence of distinctive organic remains in the rocks of this series 

 was first announced. 



Meanwhile to Prof. Hall, after the completion of the survey, 

 had been committed the task of studying and describing the 

 organic remains of the state, and in 1847 appeared the first 

 volume of his great work on the " Paleontology of New York." 

 Since 1842 he had been enabled to examine more fully the or- 

 ganic remains of the lower rocks of the New York system, and 

 to compare them with those of the old world ; and in the Intro- 

 duction to the volume just mentioned [page xix] he announced 

 the important conclusion that the New York system itself con- 

 tained an older fauna than the Upper Cambrian of Sedgwick. 

 According to Hall, the organic forms of the Calciferous and Chazy 

 formations had not yet been found in Europe, and our compari- 

 son with European fossiliferous rocks must commence with the 

 Trenton group. He however excepted the Potsdam sandstone, 

 which already, in 1842, he had conceived to be below the Upper 

 Cambrian of Sedgwick, and now regarded as the probable equi- 

 valent of the Obolus or Ungulite grit of St. Petersburg. Thus 

 Emmons, in 1842, asserted, on lithological and stratigraphical 

 grounds, the existence, beneath the base of the New York system, 

 of a lower and unconformable series of rocks, in which, in 1844, 

 he announced the discovery of a distinctive fauna. Hall, on his 

 part, asserted in 1842, and more fully in 1847, that the New 

 York system itself held an older fauna than that hitherto known 

 in the British rocks. 



It is not necessary to recall in this place the details of the long 

 and unfortunate Taconic controversy, which I have recently dis- 

 cussed in my address before the American Association for the 

 Advancement of Science in August, 1871. It is however to be 

 remarked that Hall, in common with all other American geolo- 

 gists, followed Henry J). Rogers in opposing the views of Em- 

 mons, whose Taconic system was supposed to represent either 

 the whole or a part of the Champlain division of the New York 

 system ; which included, as is well known, all of the fossiliferous 

 rocks up to the base of the Oneida conglomerate (and also this 



