314 C. JD. Walcott—The Taconic System of Emmons. 



writer would freely acquiesce in the decision, so far as the 

 British rocks are concerned. This fact is found in the exist- 

 ence of peculiar fossils on both sides of the Atlantic, which, 

 so far as discoveries have been made, are confined to the slates 

 of the Cambrian and Taconic systems ; and now the great ob- 

 ject of the writer is to show that the above question has not 

 been settled right, or according to the facts ; or, in other words 

 that the Taconic rocks are not the Hudson River slates and 

 shales in an altered state, or that all the Cambrian rocks are 

 not Lower Silurian." * 



In the following pages observations and deductions there- 

 from are given to support the above statement in relation to 

 the " Taconic System," but nothing further is said of the fos- 

 sils from the Cambrian system, and I am at a loss to know to 

 what species the author referred. Reference is made to the 

 Cambrian sections of Sedgwick, in 1856, to show that although 

 the Cambrian slates are conformably beneath the Coniston 

 limestone bearing Lower Silurian fossils, and hence may be re- 

 ferred to the Silurian, the Taconic rocks are unconformably 

 beneath the equivalent Calciferous sandrock of the New York 

 series and cannot be included with the Lower Silurian.f 



Among the letters of Dr. Emmons, published by Prof. Jules 

 Marcou4 is one, dated November 19, 1860, in which he says :§ 



" .... I do not think him [referring to Barrande] right in 

 maintaining that his Primordial group is a part or parcel of 

 the Silurian ; . . . . the Lower Silurian is strictly unconform- 

 able to every part of my Taconic series, and this series is 

 .... separate and distinct from Silurian." 



On the same page, in a letter dated November 20th, 1860, 

 he says : " On reading his [Barrande's] papers, I found that, 

 after all, his Primordial group is only Lower Silurian. I con- 

 ceive we have exactly his Primordial group in the band of 

 slates containing the Paradoxides. But this band is only a 

 very narrow belt of beds." 



In a letter dated December 28th, or 29th, | he says, when 

 speaking of the announcement of the Huronian System by 

 Logan : "I claimed that the Huronian was the Taconic Sys- 

 tem . . . Are you aware that most, if not all, of those beauti- 

 ful graptolites Mr. Hall refers to the Hudson River group be- 

 long to the Taconic System ?" 



Again, in a letter dated January 23d, 1861:1" "The acknowl- 

 edgment of the Primordial of Barrande in this country is 

 really one of the finest and best facts in geology, making a coordi- 

 nation of American and European rocks so complete and har- 

 monious." 



*Agric. N. T., vol. i. p. 49, 1847. §Loc. cit., p. 186. 



•f-Am. Geol., vol. i, pt. 2, p. 90, 1856. ||Loc. cit., p. 188. 



\ Proc. Am. Acad. Arts and Sci., vol. xii, 1885. ^[Loc. cit., p. 190. 



