lower paleozoic. 201 
From Prof. C. H. Hitchcock. 
Prof. C. H. Hitchcock writes as follows : 
Hanover, N. H., July 8th, 1887. 
Prof. Winchell : 
Dear Sir ^ * * * * Specifically (1) as to Tacouic, I am satis- 
fied from the late paleontological discoveries of Walcott (which 
agree with Emmons' paleontological work) that the lowest 
Taconic rock is of Lower Potsdam age. Hence it is not proper 
to assign any of it to the Archean. I suppose that Hunt in- 
cludes with his known Taconic, rocks of similar mineral char- 
acter which as yet have not afforded fossils, and it is these unfos- 
siliferous rocks that he refers to the Archean. I should say, 
let all the indefinite rocks, quasi- Archesm or ^uasi-Potsdam, re- 
main indefinite, in which case the local geologists will place them, 
some in one and some in another group. The Committee have 
not the ability to put uncertain rocks anywhere. 
Emmons called the Burlington, Yt., sandstones Potsdam 
(American Geology, Pt. ii., p. 128). In ray Vermont papers I 
have shown this rock to be the stratigraphic equivalent of the 
Granular Quartz, and the paleontologists have since discovered 
Olenellus in both the sandstone and the quartz. Hence we need 
not hesitate to include the Potsdam with the Taconic, whether it 
be regarded as a system or a series. 
(2) As to the name Taconic itself you have my two suggestions, 
either to say Taconic pro honoris causa, or use Potsdam ic in the 
sense of the rocks holding the first fauna of Barrande; I would 
not use the term Taconic at all as an inferior designation. Aut 
Ccesar, aut nullus. 
(3) I do not think it will be wise to drop the smaller American 
names, like Niagara. We may use the names of the Si/s(cms for 
the whole world, but not any terms of inferior grade. We can 
say Silurian the world over, but not Wenlock nor Niagara nor 
any similar name. 
' We must have a twofold nomenclature as you suggest and as I 
understand Prof. Williams. Thus we can have the time when 
Trinuckus lived for one division, the time of Paradoxides for 
another, and so on. It will be well if the paleontologist will find 
illustrations of longevity to characterize every time division. The 
trilobites furnish an illustration. They are confined to the 
Paleozoic, so the Paleozoic is the Era of trilobites. Each system 
