TABULAR VIEW. 
21 
tant rocks of our country. Heretofore they had all been termed Transition or Greywaclce, 
and no successful attempt at subdivision had been made by any European geologists ; while 
in this country, as before mentioned, all efforts had been to identify them with the published 
systems of Europe. Mr. Murchison’s work therefore shed a flood of light upon what had 
previously been a region of darkness, and gave confidence to those whose examinations were 
directed towards the subject of elucidating these deposits. 
In the Annual Report of 1840, I expressed the following opinion of the value of that work 
to the American student in lower geology : 
“ Since the publication of Mr. Murchison’s work, we have been enabled to establish with 
“ great certainty, the analogy of our rocks with those of the Silurian System, as developed 
“ in England and Wales. In this country, however, the greater undisturbed range, and ap- 
“ parently better development of particular members, with more numerous species of organic 
“ remains, enables us to limit our subdivisions within narrower bounds, and thus offer greater 
“ facility for the study of particular groups.” — “ It forms an era, and an important one in 
‘‘ the development of the older fossiliferous rocks, which have been so long enveloped in 
“ obscurity. It offers inducements to the study of the same, which have never before been 
“ presented ; since, particularly in this part of our country, the rocks of the Silurian System 
“ are better developed than any others ; while the means of studying them with guides have 
“ been entirely wanting. Thus the student, after weary months of labor, abandons the sub- 
“ ject in despair, being unable to identify the rocks or fossils with any system heretofore 
“ published ; and having made too little progress to systematize the whole, distrusts what he 
“ does know, because it seems inapplicable to what he supposes the same rocks or their 
“ equivalents in another county.” Mr. Murchison has done for the older deposits what Mr. 
Lyell has done for the more recent; and we have now in each system standard groups of 
reference, which, so far as examinations have progressed, hold true over extensive districts 
of country. 
Mr. Murchison, in company with M. de Yerneuil, has since been investigating the same 
formations in Russia ; and he mentions, in a letter, the occurrence of rocks in Siberia, 
charged with Pentamerus Knightii, a fossil abundant in a particular position in England. 
Formations of the same age have long been known in Sweden and Norway, Canada and va¬ 
rious parts of North America, extending far westward ; and during the past year, I have traced 
the groups as developed in New-York, throughout the country intervening this State and the 
Mississippi river, and thence into the territory of Iowa. The occurrence of fossils typical 
of the lower part of this great series, shows its extension over an extremely wide area. 
Fossils from Lake Huron, Lake Winipeg, and several points of the far northwest, all indi¬ 
cate the existence of rocks equivalent to the Lower Silurian of England, or the Champlain 
division of New-York. Mr. Stokes, in a paper “ On some species of Orthocerata,” publish¬ 
ed in the Geological Transactions, speaking of the localities, and the circumstances under 
which they were collected, remarks : “ It will be observed that these American localities are 
“ widely separated from each other, and are not parts of a continuous deposit; but the agree- 
“ ment in character of the limestone rock, and of the fossils, shows that they are of the 
