456 TRANSACTIONS OF SECTION C. 
and Hopteria; the gasteropods, by Ophileta, Maclurea, Huomphalus, Holopea, 
Hormotoma, Ectomaria, Murchisonia, Lophospira, Buconia, Raphistoma, Helico- 
oma; the cephalopods, by Orthoceras, Cyrtoceras, Gomphoceras, Piloeceras, 
T'rocholites. Of the foregoing genera many of the species are common to this 
region and the North-West Highlands of Scotland. 
The trilobites associated with this fauna comprise the genera Dikelocephalus, 
Bathyurus, Asaphus, Harpes, and Nileus. 
In Northern Newfoundland, in zones F to N of Billings, this fauna, with 
localised species, is found in great development, in limestones and dolomites 
resembling those of Durness. Its upper limit is there clearly defined, for the 
limestones and dolomites are overlain by dark shales containing graptolites of 
undoubted Arenig age. 
A careful comparison of the faunas of the Durness and Beekmantown lime- 
stones shows that the assemblage of fossils in the Balnakiel and Croisaphuill 
groups of Durness is practically identical with that in the zones F to N of 
Billings, as developed in Newfoundland. These groups must therefore be older 
than the Arenig rocks of Wales, and must represent at least the Welsh Tre- 
madoc strata, if not part of the Lingula Flags, both of which, according to the 
English classification, are grouped with the Cambrian system. 
But even in the purely European province of North America, in New Bruns- 
wick, where the Beekmantown calcareous fauna is entirely absent, and where 
the faunal sequence and type of sedimentation are almost identical with those 
of North Wales, the basal Ordovician or Lower Silurian rocks of American 
geologists include the Peltura scarabwoides and the Parabolina spinulosa zones, 
which, in Wales, are classed with the Lingula Flags. It is obvious, therefore, 
that the boundary-line between the Cambrian and Ordovician (Lower Silurian) 
systems is not drawn at the same stratigraphical horizon by American and 
British geologists. In fixing the age of the Durness dolomites and limestones 
the English classification has been adopted. 
The paleontological evidence now adduced regarding the relation of the 
Cambrian fauna of the North-West Highlands to that of North America leads 
to the following conclusions :— 
1. The Lower Cambrian fauna of the North-West Highlands, distinguished 
by the genus Olencllus and its associates, is almost identical in character with 
that of the Georgian terrane of the western life-province of North America, 
and essentially different from the Lower Cambrian fauna of the rest of Europe. 
2. No forms characteristic of the Middle Cambrian division, either of Europe 
or North America, have as yet been found in the North-West Highlands; but 
this division may be represented by the unfossiliferous dolomites and limestones 
of the Ghrudhaidh, EKilean Dubh, and the lower Sail Mhor groups. 
3. The fossiliferous bands of the Sail Mhor group may be the equivalents of 
the lower part of the Upper Cambrian formation. 
4. The Balnakeil and Croisaphuill groups of the Durness dolomites and 
limestones contain a typical development of the molluscan fauna of the Beek- 
mantown limestone, belonging to the western life-province of North America. 
As the Beekmantown limestone is succeeded by shales, with Arenig graptolites, 
it follows, in accordance with British classification, that these groups must be 
of Upper Cambrian age. 
5. The highest subdivision of the Durness limestone (Durine) has not yielded 
fossils of zonal value, and the members of this group are not overlain in normal 
sequence by graptolite-bearing shale or other sediments. 
Cambrian Palcogeography between North America and North-West Europe. 
In attempting to restore in outline the distribution of land and sea in Cam- 
brian time between North America and North-West Europe reference must be 
made to various investigators whose researches in paleogeography are more or 
less familiar to geologists. Among these may be mentioned Suess, Dana, De 
Lapparent, Frech, Walcott, Ulrich, Schuchert, Bailey Willis, Grabau, Hull, 
and Jukes Browne. The views now presented seem to me to be reasonable in- 
ferences from the paleontological evidence set forth in this address. 
In the North-West Highlands there is still a remnant of the old land surface 
upon which the Torridonian sediments were laid down. There is conclusive 
