the Taconic System, &c. 211 
the names of Atops trilineatus and Elliptocephala asaphoides. The 
others were graptolites, fucoides and apparently trails of anne- 
ides; he considered all the species to be distinct from any that 
had been found in American rocks of undoubted Silurian age. 
The pre-silurian age of the formation has also been maintained 
by him in several more recent publications such as his ‘‘ Ameri- 
can Geology ”—the several reports on the geological survey of 
North Carolina and in his “ Manual of Geology.” 
On the other hand, Professor Hall placed the whole region in 
the Hudson River group. In the first yolume of the Palzontol- 
ogy of New York he identifies Aiops trilineatus with Triarthrus 
Beckii the characteristic trilobite of the Utica slate ;—Hihipto- 
cephala asaphoides he refers to the genus Olenus and describes as 
congeneric therewith another trilobite (O. undulostriatus) said to 
be from the true Hudson River shales. It is scarcely necessary 
to state that these identifications have always afforde Ro. 
tremely powerful objection against the correctness of the position 
assumed mmons, because no species of trilobite is known to 
range from the Primordial Zone up to the top of the Lower Si- 
urian. Hfall’s first volume was published in 1847 and as it is 
Unquestionably the most important work on the Lower Silurian 
Fossils of North America it has been very generally accepted 
by our physical geologists as a guide. It is not surprising there- 
fore that, in all the discussions that have taken place during the » 
last fourteen years upon the age of these rocks, the majority of 
those who did not profess to be naturalists should have arranged 
themselves on the side of the leading Paleontologist of the 
countr E 
The formation was traced from New York through Vermont 
and there identified, by Prof. Adams the State Geologist, with 
the Hudson 
it with great labor through a mountainous and partially unin- 
habite country for nearly five hundred miles Phen from the 
and thence along the south side of the St. Lawrence to the mouth. 
of that river at Cape Gaspé. In Canada the nomenclature of the 
ew York Survey was adopted for all the formations and it ap- 
Pears from his several reports that Sir W. E. Logan could ie 
ae 
Ae be seen by the following correspondence that the new 
eros upon the question of the age of these rocks by 
; Bn nmorery of a large number of fossils near Q 
to P 
