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THE 



AMERICAN JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



Art. XXII. — On Lower Silurian fossils from a limestone of the 

 original Taconic of Emmons ; by James D. Dana. 



TRead at the meeting of the American Association at Ann Arbor in August, 



1885.]* 



The Lower Silurian fossils hitherto reported from rocks of 

 the Taconic system have come either from localities to the 

 north of the original Taconic area, in the State of Vermont, Or 

 from others to the southwest of it, in Dutchess County, New 

 York. The discovery of fossils which I have now to announce 

 was made the present season in a limestone of the original 

 Taconic series of Professor Emmons, his " Sparry limestone," 

 within a mile and a half of the Massachusetts boundary. 



That the facts may be fully understood as to what is the 

 original and, therefore, true Taconic, a brief review of the sub- 

 ject is here introduced.; for mistakes are still continually made 

 by writers on the subject. 



Professor Emmons, in his first account of the " Taconic Sys- 

 tem," which makes thirty pages of his Report (in quarto) on 

 the Geology of New York, published in 1842, — mentioned as 

 the constituent rocks, commencing on the west : (1) "Taconic 

 slate," in eastern New York, including the Hoosic slates ;f (2) 



* Some changes have since been made in order to include the facts from addi- 

 tional observations on the fossils and rocks of the region. 



f Of this division of "Taconic slate," his No. 5, in the tabular statement on 

 page 144, Prof. Emmons says, on page 150, "No organic remains have been fouDd 

 in the rocks; it is even destitute of those obscure markings which are called 

 fucoids." 



A.M. Jour. Sci.— Third Series, Vol. XXXI, No. 184.— April, 1886. 

 16 



