404. =R. I. Murchison on the Silurian Classification. 
Arr. XLIL—A few Remarks on the Silurian Classification ; 
by Str Ropertcx Impry Murcuison, G. C. St. S., F.R.S., 
Memb. Imp. Acad. Soc. of St. Petersburg, Cor. of the Roy. 
Inst. France. : 
Belgrave Square, March 3, 1847. 
TO THE EDITORS. 
_Gentlemen—I have sent to you, through your booksellers, a 
copy of my last memoir on the Silurian Rocks of Sweden, which 
may prove interesting to some of the American geologists on 
account of the distinctness which it establishes between the 
lower Silurian strata of the continent of Scandinavia and the 
isle of Oland, and the upper Silurian of the large island of Goth- 
land, which I have placed in detailed parallel with our Wenlock 
and Ludlow rocks of England. In calling your attention, and 
? 
species of trilobites, the lowest fossiliferous beds resting on slaty 
grauwacke, without fossils, to which the author applies the term 
Cambrian : ; 
I call your notice to this last mentioned fact, (intending to visit 
Bohemia in company with M. de Verneuil, in the ensuing sum- 
mer, ) because I have, in the course of this winter, been compelled 
for the first time to defend my “Lower Silurian” against a new 
proposal of Professor Sedgwick, which almost amounts to the 
suppression of the term, and the substitution, in its place, of the 
word “Cambrian.” T'o this proposition I am entirely oppose 
The latter term was suggested a year after I gave my first gen- 
eral view of the upper and lower Silurian rocks (in 1835) as form- 
ing one natural system, and the word Cambrian was afterwards 
— oe Oa Oe 
* The MS. did not enable us to ascertain this name. 
