164 N. H. Winchell on the Taconic 
opponents; they simply adhered to and repeated then" arguments, 
based on old data.' Pie, however, was not idle, but had re-ex- 
amined all the facts and arguments upon which the Taconic was 
supposed to rest, revisiting many of the localities in the field 
where his earlier investigations had been made, and extending his 
researches to Rhode Island and Maine, and secondarily to Michi- 
gan. In this revision he greatly modified and amplified the 
Taconic system. He availed himself of the law which allows 
a paleontologist to revise his original description. He does not 
change in the least the original idea, the prc-Potsdain age of the 
system^ but he introduces important internal re-arrangements, 
limits the different members, gives them different mutual rela- 
tions, and describes them all more fully. He now claims that the 
Taconic occupies "the true paleozoic base," — that it, and "the 
slates of the Cambrian," notwithstanding the announcement of 
Mr. Murchison that the whole of the Cambrian is covei'ed by the 
Silurian, are marked by "the existence of peculiar fossils on both 
sides of the Atlantic." He gives diagrams of the strata that 
exhibit the unconformity of the Taconic with the Calciferous 
sandrock, the great difference in age between the Taconic and 
the Hudson River slates, mentioning fossils of the latter and of 
the Trenton within the general area of the Taconic, and calls 
attention to this anomalous fact. These sections run eastwardly 
from Whitehall, and Greenbush, N. Y. In this revision he de- 
scribes and figures two new trilobites as characteristic of the 
Taconic — Atops trUincatits and Hll'iftoccpliala asaphoides^ in 
which he preceded, both in the generic and the specific names, 
all other designations of these fossils, though the generic names 
have since been removed bv Mr. Walcott and replaced respect- 
ively by /'/yr/^fS^ar/a and Olenell us descrxhcd several years later.^ 
These are now well-known as primoi'dial trilobites, belonging in 
the "Georgia formation" of Vermoiit, Thev were found by 
Dr. Fitch in Washington countv N. Y. near the base of Bald 
mountain. 
' Among his opponents, some of whose opinions he quotes at length, 
Dr. Emmons mentions Mather, Hitchcock, Dana, W. D. and W. B.Rogers 
and Murchison. 
- Bulletin No. 30, U. S. Geol. Surv. 
