R.I. Murchison on the Silurian Classification. 405 
applied to the masses lying beneath the “ Lower Silurian,” which 
might be found to be characterized by a distinct group of organic 
remains. Subsequent researches, however, in various parts of 
Europe and America, have shown that no typical fossils can be 
detected in any of the lower strata differing from those by which 
I characterized the lower Silurian, and hence, on the principle of 
“strata identified by fossils,” I have for some years past main- 
tained, in all my publications, that the base line of the Silurian 
rocks so descended as to embrace the earliest clear traces of or- 
ganic life. The government geologists of Britain, under Sir 
Henry De la Beche, have pointed out, that throughout South 
Wales, the very strata which I had described as “ Lower Silurian,” 
fold over and over, and occupy large tracts, to which I had, in 
my first work, erroneously applied the word “Cambrian ;” and 
now these same surveyors, particularly Mr. Ramsay and that able 
paleontologist, Professor Edward Forbes, assure me, that through- 
out orth Wales, from Bala to Snowden, the rocks which 
had hoped might be typified by other or “Cambrian” fossils, are 
charged with the same lower Silurian forms, and often with the 
very same species which are described by me as occurring in my 
Carodoc sandstone or Llandeilo Flags. They further confirm 
my original views of classification, in stating that these North 
Welsh strata, whether lower or upper Silurian, are so linked 
together, that they form one natural system; there being found 
many more species common to the upper and lower division than 
I ae able to detect, when I completed the Silurian system, 
in 1839, | 
Now, whilst my memoir on Gothland demonstrates the identity 
of its upper Silurian functions with those of Britain, the labors 
of our government geologists are daily opening out new features 
of comparison between the ‘“ Lower Silurian” of Russia and Scan- 
dinayia, as described by de Verneuil, Keyserling and myself, and 
the North and South Welsh strata. Thus the Cystidea, those 
earliest forms of Crinoids, with which I was unacquainted when 
the Silurian system was published, and which occur in myriads 
in the lower Silurian limestone around the Baltic, have been 
found pretty abundantly near Bala, Harefordwest, é&c.; and 
among them is the very species, Echino-spherites ( Spheronites ) 
aurantium, which abounds in Russia and Sweden. It follows, 
therefore, that the terms which I was the first to propose must be 
adhered to, particularly as I have myself applied them to very 
large regions of Europe, on fair inductive evidence, and that 
North American geologists have honored me by doing the same 
im their country. ; a 
gain, whilst no zoologist has attempted to define any distinct 
types of life of earlier date than the lower Silurian, so 1s it im- 
possible (at least in any region which I have seen) to separate 
