12 
SILUEIA. 
[Chap. I. 
look to the lithological structure of the Scottish rock, we cannot discover 
any close relationship between it and the Upper Laurentian rock of Canada, 
or Labrador Series;' for this last is essentially composed of felspars, 
often rich in alkalies, especially soda, and is thereby markedly distinguished 
from the British formation, which, throughout its range, from Cape Wrath 
to Lochs Broom, Torridon, and Maree, as also in the island of the Lewis, is 
a granitoid, massive gneiss, in which hornblende and quartz predominate 
very largely over felspar and mica. Like the grand Lower Laurentian of 
Canada, it contains limestone ; but instead of the thick development of 
calcareous matter of the American deposit, the limestone layers in it are 
thin, fissile, and of very jrare occurrence. Hence we might well have 
expected that if any traces of organic bodies were to be detected in rocks 
of this age, previously termed 'Azoic they would be found in those ex- 
tensive and thick masses of limestone which occur in the Lower Laurentian 
of America. Thus, whilst it is in them that the Rhizopod named Eozoon 
Canadense by Principal Dawson* has been detected, our chances of dis- 
covering this little fossil in our attenuated and scaly British limestone 
are slight indeed. Yet this same zoophyte, which, like the polyps of 
succeeding epochs, and of our own day, formed ledges or layers incrusting 
the most ancient known rocks, has been recently detected, by MM. Giimbel, 
Fritsch, Hochstetter, and Eeuss, in the limestone of the older gneiss of 
Bohemia and Bavaria. I may here be excused for stating that, in 1862, 
when I explored for the last time the mountains of Bohemia, I placed that 
same gneiss, of which there are two sorts, on the parallel of the Lau- 
rentian of America and Scotland. For I felt assured, by the infraposition 
of the rocks in both countries to the other recognized palaeozoic groups, 
that their age must be pre-Cambrian. For example, when I saw in 
Bohemia and Bavaria enormous masses of clay-slate, mica-schist, <fec. lying 
beneath Barrande's ' Zone Primordiale,' — masses which obviously occupied 
the place of the 4 Cambrian ' of the British Geological Survey, and reposed 
upon primordial gneiss, I could draw but one inference ; and hence I 
affirmed that these rocks of Central Germany were of Laurentian age, — 
and this before they were so styled by any other author, and long before 
an Eozoon was found in them f . 
Further, I have recently learned from Dr. Geinitz that the Eozoon has 
been also discovered in the crystalline limestone of Maxen, in Saxony, south 
of Dresden. Thus we now know that in the heart of Europe, as in Ame- 
rica and Britain, there exists a nucleus of the oldest traceable stratified 
rock, around and over which the succeeding Palaeozoic formations have 
been accumulated. 
There is also little doubt that in the northern and central parts of Nor- 
* Quart. Journ. Geol. Soc. vol. xxi. p. 54 ; vol. xxii. t See my memoir on the Gneiss and superjacent 
p. 609, &c. Canadian Naturalist and Geologist, PalsBozoic Formations in Bavaria and Bohemia, 
April, 18(55. Intellectual Observer, No. 40. ro- Quart. Journ. Geol. Soc. vol. xix. p. 359. 
pular Science Ecview, No. 15, &c. 
