Murchison’s Siluria. 405 
In Australia, where a very short time since reference could be 
made only to rocks of the Carboniferous and Devonian age,* we 
hear of true Silurian strata containing fossils like those of the 
British Isles. Some species seem undistinguishable.t 
In South America, the lofty Cordilleras and plateaux, whose 
mineral characters had been so admirably described by Humboldt, 
are shown by Alcide d’Orbigny to consist in great part of such 
ancient sediments. Still more clearly has North America been 
found to contain a vast succession of these paleozoic rocks, and 
especially of their lower members. Numerous geologists of the 
United States have demonstrated, that their ancient strata fol- 
lowed the same order on avery grand and usually unbroken 
scale (particularly in the western region); doubtless due to their 
aving been exempted in such tracts from the intrusion of igne- 
iferous slates, limestones and sandstones Sai on ‘eecties 
rocks, which, extending far northwards, are surmounted by other 
sedimentary masses similar to strata of the United States, and 
where Silurian fossils have been detected in limestones amid the 
polar ices. Adjacent to the southern end of this continent, simi- 
lar remains have been collected by Darwin in the Falkland 
slands. 
In few of those regions, however, with the exception of North 
America (certainly not in the British Isles, where the strata are 
in many parts much obscured by igneous outbursts), is the se- 
quence so undisturbed as in Scandinavia and European Russia. 
There, the successive primeval deposits extend over a large por- 
tion of the earth in regular sequence and in an unaltered state. 
Hence, though to the unskilled eye, Russia presents only a mo- 
notonous and undulating surface, chiefly occupied by accumula- 
tions of mud, sand, and erratic blocks, its framework, wherever 
it can be detected, exhibits a clear ascending series. "The older 
sedimentary strata, uhvahes only slightly from horizontality, are 
there overlaid by widely-diffused masses of those Permian rocks 
which constitute the true termination of the long palzozoic 
period, 
Scription of the Bohea mountains, without sus octing, © that a fine primeval sueces- 
sion may “gee be found. For the Chinese Poet Sips vidson, Quart. Journ. Geol. 
tat og vol, ix, p. 353; and de Koninck, serene rege vol. xiii, pt. 
f See Strzelecki’s Australia, Foss. Fauna, Morris; M’Coy, Ann. Nat. Hist. 1847. 
Also Dana’s Rep. Geol. Expl. Exp., >, wie ere many new species are described —. 
en Memoir by the Rev. W. Clarke, Quart. Journ. ao 1. Soc. Lond., vol. viii; see 
¢ See particularly the sent of Jarhes Hall saat 4 D. Dale Owen, the Reports of 
Logan—the chief geologist of Canada. 
