Chap. XVIII. DEVONIAN KOCKS IN NOVA SCOTIA ETC. 
439 
Devonian Rocks of Nova Scotia and New Brunswick. — An extensive and com- 
plicated series of this age has been ascertained to exist in Southern New Bruns- 
wick ; and Dr. Dawson has recognized an equivalent of the lower member of the 
series, or the Oriskany Sandstone, at Nectaux in Nova Scotia, where it contains 
extensive deposits of iron-ore. These rocks do not, however, correspond litho- 
logically either with the Devonian of New York, or with the Gaspe sandstones 
which represent this period in Eastern Canada. The deposits of the period 
which elapsed between the close of the Upper Silurian and the beginning of the 
Carboniferous, though on a large scale as to thickness, would appear in Eastern 
North America to have little horizontal uniformity over large areas. This feature 
harmonizes with the fact that the period was characterized by the eruption of 
great granitic dykes and masses, and also by a luxuriant land-flora indicating ex- 
tensive terrestrial surfaces. Dr. Dawson has, within a few years, described no 
less than eighty-two species of Land Plants from the Devonian rocks ; and of these 
probably ten ascend to the Carboniferous system, while two occur in the Upper 
Silurian. The greater number of the species occur in the Upper Devonian. 
The genera specially Devonian are principally Psilophyton, Leptophlceum, Pro- 
totaxites, Syringoxylon, and Nematoxylon, while the greater part of the species 
belong to genera well known in the Carboniferous rocks, as Lepidodendron, Da- 
doxylon, Cyclopteris, Neuropteris, Sigillaria, &c. j indeed nearly all the leading 
Carboniferous genera are represented *. 
Among the important conclusions of Dr. Dawson are the following : — 
With few exceptions, the generic types of the Devonian and Carboniferous 
periods are the same, six out of the thirty-six genera only being peculiar to the 
Devonian deposits. In the ascending order there is always a constant gain in 
the number of genera and species. That a large part of the difference between 
the Devonian and the Carboniferous floras is probably referable to different geo- 
graphical conditions, the land of the Devonian having probably been of a more 
upland and truly terrestrial character than the swampy flats on which the vege- 
tation of the Coal-period grew. On this head I have already made an allusion 
to the tracts of the supposed Upper Old Red Sandstone of the North-east of 
Scotland (p. 270). 
For a better acquaintance with these Devonian rocks, so very rich in fossil 
Plants, and with their great development towards the close of that epoch, the 
reader must consult the instructive memoirs by Dr. Dawson. I have only to ob- 
serve that his general conclusions do not materially differ from those which 
Bronn, Goppert, and Unger have drawn from an examination of the Devonian 
flora of Europe. 
It is interesting to add that the Devonian strata of the vicinity of St. J ohn's 
have afforded to Mr. C. F. Hartt the only remains of Insects hitherto found 
in rocks older than the Carboniferous. From a note by Mr. Scudder, in the 
excellent Report on the southern part of New Brunswick by Professor Bailey, 
it would appear that fragments of five species have been found, all probably 
Neuropterous. One is a member of the group Ephemerina, several times larger 
than any modern species. 
North-western and Arctic America. — In taking a general view of the physical 
structure of the northernmost portion of America, the late Sir John Richardson, 
the great Arctic traveller, considered that, on the whole, the granitic and 
crystalline rocks of the central and eastern countries of the Hudson's Bay ter- 
* Dawson, 'Flora of Devonian Period,' Quart. Journ. Geol. Soc. vol. xviii. and vol. xix. 
