CD. Walcott — The Taconic System of Emmons. 321 



On page 63, of the Agriculture of New York (vol. i), under 

 the heading " Black Slate," Dr. Emmons says : " I shall de- 

 scribe the rocks in the descending order : and by so doing, I 

 commence with the mass of which there is some doubt whether 

 it ought to be considered as a distinct rock or merely the 

 upper portion of the Taconic slate ; still I am disposed to re- 

 gard it now as a separate and distinct rock, forming, so far 

 as examinations have been made, the highest member of the 

 Taconic system. Circumstances which have led to the separa- 

 tion of this from the rock referred to are of an interesting 

 character ; interesting particularly as being connected with 

 the discovery of crustaceans where they were least expected." 



Dr. Asa Fitch found the fossils from the " Black Slate," in 

 1843, and gave them to Dr. Emmons, who described two spe- 

 cies of trilobites under the names of A tops trilineatus and 

 Elliptocejphala asa/phoidesj the first he thought to be an inter- 

 mediate genus between the Calymene and Triarthrus ; of the 

 second, Elliptocejphala asajphoides. he compared parts with 

 similar parts of the Asajphus tyr annus, of the Lower Silurian 

 of England.* 



On page 68 of the same memoir, under the head of " Fossils 

 peculiar to the Taconic Slate," he describes two species of 

 Annelid trails : one. from the Green Taconic slate, and the 

 other from the sandstone in Washington County. He follows 

 this with a description of nine species of what appeared to be 

 trails from the slates of Waterville, Maine. It appears from 

 this that Dr. Emmons considered these various trails to be 

 " fossils peculiar to the Taconic slate," and that the trilobites 

 which he described he did not consider, at that time, as typi- 

 ical of the " Taconic System," for he says (loc. cit., p. 64), in 

 speaking of the " Black Slate :" "Assuming that its fossils are 

 distinct from the fossils of this and other systems," etc. 



In his conclusions, he says :f " The Nereites and other fos- 

 sils of the Taconic slate are unknown in any of the members 

 of the Champlain group. In addition to which, it is impor- 

 tant to bear in mind the fact that in this group the Mollusca 

 of the New York system are also wanting." 



In 18564 he referred the Black slates to a position above the 

 Talcose slates of the " Lower Taconic," thus making them the 

 base of the "Upper Taconic" series. On page 98, loc. cit., 

 the argument is made that the " Taconic System " is peculiar 

 in its contained organisms, and that he has the right to con- 

 sider the absence of certain Silurian fossils as evidence that 

 the Taconic was not of Silurian age. As has been shown in 

 the first part of this paper, the limestones of the " Lower Ta- 



* Loc. cit., pp. 64, 65. . % Am. G-eol., pt. 2, p. 49. 1856. 



f Loc. cit., p. 108. 



