wel 
others are to narrate their facts. Steps of this kind have formed, 
and must form, the great epochs in the progress of all sciences of 
classification, and especially in ours ; and I need not remind you how 
great the importance and the influence of such steps amongst you 
have been. To pronounce at once upon'the success of such steps 
must always be in some degree hazardous; since their success is in 
fact this, that they influence permanently and powerfully the re- 
searches, descriptions, and speculations of future writers ; and there 
are few of us who can pretend to the foresight which might enable 
us to say, in any special case, how far this will be so. Yet the great 
works of Messrs. Murchison and Sedgwick, tending to the establish- 
ment of a classification of the strata below the old red sandstone 
(works which, on all accounts, we must consider as a joint under- 
taking), appear already to offer an augury which can hardly be 
doubtful, of this influence and permanence. Mr. Murchison’s ap- 
pellation of the “Silurian System” has already been adopted by 
“MM. Elie de Beaumont and Dufresnoy, who have given it currency 
on the continent: M. Boué and M. de Verneuil announce the dif- 
fusion of “ Silurian” rocks in Servia and the adjacent parts of Turkey 
in Europe; our own members, Mr. Hamilton and Mr. Strickland, 
have extended their range to the Thracian Bosphorus; M. Forch- 
hammer, of Copenhagen, visited the “ Silurian region” to endeavour 
to recognize the rocks of Scandinavia; and MM. Omalius D’Halloy 
and Dumont have just explored it, to establish a parallel between 
its deposits and those of Belgium. It will be observed that some of 
the districts thus mentioned are out of the limits of our geological 
Home circuit ; and if the identification be really and permanently 
established in these cases, will extend the limits within which the pa- 
rallelism of geological series can be asserted: and this is, in effect, 
what we have a right to look for, sooner or later, in the progress of 
geological science. As we must be careful not to apply our domes- 
tic types without modification to other regions, so must we take care 
not to despair of modifying our scheme, so that it shall be far more 
extensively applicable than it at first appeared to be. Of this pro- 
gress of things examples are too obvious and too recent to require 
to be pointed out. 
The labours of Professor Sedgwick refer to the “Cambrian System,” 
which lies beneath the Silurian System, occupying much of North 
