374 Murchison’s Siluria. 
with those of England. Nothing could have been more opportune 
for American geologists than the promulgation of the Silurian Sys- 
tem. ‘The study of our fossiliferous rocks had just been. seri- 
ously commenced in this country by the organization of the ge- 
ological surveys of the great states of New York and Pennsylva- 
nia, which are chiefly occupied by the strata of the same age as 
those studied by Murchison, but developed on a vastly greater 
scale and in a much completer sequence. At this time the great- 
est confusion prevailed in regard to the position, age and nomen- 
clature of our palzozoic strata. The Silurian and Devonian 
ocks of Pennsylvania were simply designated as “ secondary” 
by the State Geologist in his first report (1836). In the same 
year Mr. Featherstonhaugh described all the rocks of the North- 
west, including the whole series from Lower Silurian up to the 
coal, as being of carboniferous age, and in his report for the pre- 
vious year he had made still greater confusion in attempting to 
classify the rocks of the Atlantic States. Troost had also consid- 
ered the Silurian of Tennessee as carboniferous, and Eaton had 
identified rocks of the same age in New York as of the age of 
the New Red Sandstone. 
Great was the impetus given to paleozoic geology by the es- 
tablishment of the Silurian System, and geologists every where 
began to search among their transition and grey wacke rocks for 
the equivalents of the group, established by Murchison. No one 
however was more active in extending his system to foreign coun- 
tries than our author himself, and with the especial object of 
finding fresh confirmation of the truth of the British palseozoic 
classification he visited Russia, and with the aid of de Verneuil 
and under the especial patronage of the Emperor, carried out, 10 
the years 1840 and 1841, an extensive survey of Russia in Bu- 
rope and the Ural mountains. In 1842, ’3 and ’4, farther invest- 
gations were made by Count von Keyserling in Russia a 
Murchison himself in England, Germany and Scandinavia, and 
in 1845 the results of these laborious and costly researches ap- 
peared in the form of two quarto volumes entitled “ The Geol- 
ogy of Russia in Europe and the Ural Mountains,’ a work print- 
ed and illustrated in a style of traly imperial magnificence. Be- 
sides this work and the “ Silurian System,” numerous papers by 
Murchison, either alone or associated with Sedgwick or Verneuil, 
appeared in the transactions and proceedings of the Geological 
Society of London, in the preparation of which the aid of the 
most accomplished paleontologists of England was obtained 18 
their various departments. 
The results of all these researches are presented by the author 
in a condensed form in the work now before us, an odtavo of 
of the 
523 pages, evidently prepared with the object of panes : 
