6 
PALAEOZOIC ROCKS IN OTHER PARTS OF THE WORLD. 
Judging from the numerous Orthoceratites and Trilobites long since supplied 
to us from the British colonies of North America, we were, indeed, well aware that 
the strata to which we affixed the term Silurian must there have a very wide ex- 
tension ; and this general point was sustained by the publication of numerous 
Silurian fossils from that region by M. de Castelnau 1 . But even whilst we write, 
new data crowd upon us from the researches of Mr. Logan and Captain Bayfield, 
which more clearly indicate the exact nature of the palaeozoic succession in those 
regions, and show us how analogous it is to that of Europe. The Lower Silurian 
rocks are well-developed at the Falls of Niagara and in various parts of the Canadas 
and Nova Scotia, where they rest, it appears, on gneissic and granitic rocks, just 
like similar beds in Scandinavia, which are described in the next chapter. The 
northern side of the Gulf of St. Lawrence is composed of more ancient crystalline 
rocks, whilst the Lower Silurian occupy the isles of Mingan and Anticosti. In the 
collections made in these islands by Captain Bayfield, we were delighted to recognise 
our Russian friends Illamus crassicauda, Orthoceratites duplex, Spirifer lynx and Lep- 
trena Humboldti, and still more to find that this group was there (as in England and 
Scandinavia) overlaid by limestones containing the Pentamerus oblongus. Again, 
the north coast of Newfoundland offers a like succession, for near Norman Cape 
the Orthoceratites duplex and Euomphalus qualterlatus , both characteristic Lower 
Silurian types in Russia, are associated with other Orthoceratites and chambered 
shells, some of which are allied to Nautili and Lituites, as in the Bay of Chris- 
tiania. The same enterprizing naval surveyor (Captain Bayfield), has further 
observed the junction of the lowest Silurian deposits with the subjacent crystal- 
line rocks along a frontier of not less than 2000 miles, or from the Straits of Belle- 
isle on the north-east, to the end of Lake Superior on the south-west 2 ; whilst from 
this grand base-line, an ascending succession has been traced eastwards and south- 
wards, through Upper Silurian and Devonian, to the Carboniferous deposits of New 
Brunswick and the United States. 
Extending our views from North to South America, we have to thank M. Alcide 
d’Orbigny for a splendid geological work, in which he has endeavoured to sketch 
out, through many degrees of latitude, the great subdivisions of the Silurian, De- 
vonian and Carboniferous series ; whilst Mr. C. Darwin had long ago satisfied us of 
the existence of Lower Silurian rocks in the Falkland Isles. We can now there- 
fore affirm, that throughout the western hemisphere, from the far north to isles 
1 Systeme Silurien de l’Amerique Septentrionale. 
2 See Memoir read before the Geological Society of London, March 1845. 
