198 EEPORT OF THE AMERICAN COMMITTEE. 
are given below, or are summarized so that their substance and 
evidence are expressed. 
Prof. J. D. Dana's Views. 
New Haven, March 17tli, 1888. 
Prof. N. H. Winchell, : 
My Dear Sir : 
******* 
My conclusions with regard to the Taconic formation, now 
fully sustained by the new discoveries of Walcott, are, as set 
forth in my papers, that it includes the whole of the Murchl- 
sonian "Lower Silurian," that the chief part of it is above the 
now-called Cambrian ; but that the quartzite, the least character- 
istic part in the 1842 Taconic, is a proraiment member of it. It 
lies directly beneath the limestone, and probably covers not only 
the Middle Cambrian, but also the true Potsdam, if not simply 
the equivalent of the Potsdam. 
As to the use of the name Taconic for the Cambrian, or for 
any part of it, or any part of the Lower Paleozoic, there is, in 
favor of the term, that it is short, is familiar, and has been 
employed for all parts of the " Lower Silurian." But I believe 
it will be regarded after awhile as a reminder of Emmons's blun- 
dering work — a succession of unstudied assumptions that brought 
only evil to the science. For his reputation I would say that 
the sooner the name disappears from scientific nomenclature the 
better. 
I think that there would be nothing gained by substituting 
Taconic for Cambrian ; and also that the attempt to make such 
a substitution would be fruitless. The use of the term for either 
subdivision of the Cambrian would not be well because no sub- 
division of it stands out in the Taconic so prominently as to 
suggest it. It could be used with least objection, for the Lower 
Silurian, above the Cambrian, in place of the disagreeable terra 
Ordovician or Ordovian. 
It could properly be used also for the whole of the Murchi- 
sonian " Lower Silurian," that is, be made to include the Cam- 
brian and tlip Lower Silurian as some now write it. In this case 
the Paleozoic below the Devonian would embrace the Silurian = 
Upper Silurian ; and the Taconic = Lower Silurian, the latter 
