4 PALAEOZOIC CLASSIFICATION APPLIED TO NORTH AMERICA. 
from T.Caractaci. The assiduous exertions of M. Barande have thus demon- 
strated by fossil evidences, what we longed to have the power to assert, — the 
presence of an unequivocal Silurian system in the very heart of Germany 1 . 
In France the oldest palaeozoic rocks are also Silurian, but owing to the meta- 
morphosed nature of many of the tracts in which they occur, it has not yet been 
practicable to work out accurate boundary-lines between the different subdivisions 
in ascending order ; particularly on the flanks of the Pyrenees. We are, however, 
sanctioned by the distinguished authors of the great geological map of France 2 
in believing, that, on the whole, a succession like that in the British Isles pre- 
vails. From our own knowledge we should be disposed to state, that in Brittany 3 
and the adjacent tracts of Normandy, strata of Devonian age (Nehou, Ize, La 
Bacconiere, &c,), containing many fossils in their calcareous members, repose upon 
great masses of slaty schists and quartz rock, which at Angers, La Hunaudiere, 
Bain and Vitre in Brittany, and Siouville and May in Normandy, are charged with 
Silurian Trilobites and Graptolites. Among the characteristic and abundant Trilo- 
bites are the Cahjmene Tristani, Ogygia Guettardi, and a large Illsenus approaching 
to I. crassicauda, though considerably larger, and named by M. Burmeister, 
I. giganteus 4 . 
In the Boulonnais the palaeozoic series has already assumed the Belgian and 
Rhenish type 5 , exhibiting a clear descending order from a Carboniferous to a 
Devonian formation, each loaded with typical fossils, and underlaid by ill-deve- 
loped Upper Silurian shale with Graptolites. 
In comparing the Silurian deposits of different parts of France with those of 
Spain, it is interesting to observe, that the Silurian type of Brittany is extended 
southwards into the north-western territories of Spain, particularly the Asturias. 
1 Whilst we write, we find that M. Emmerich has just published an important memoir on Trilobites, 
through the aid of which class of fossils only he recognises the different stages in palaeozoic series ; and 
his op’inion agrees with the conclusion at which we arrived on the spot, that the rocks of Prague are Silu- 
rian (see Leonhard’s Journal, 1845). 
2 M. Dufrenoy and M. Elie de Beaumont. M. Durocher has recently attempted to divide the palaeozoic 
rocks of the Pyrenees, but without reference to fossils. Ann. des Mines, tome viii. 
3 Whilst Mr. Murchison was visiting the interior of Germany and Poland (anno 1843), M. de Ver- 
neuil, accompanied by M. d’Archiac, was examining the palaeozoic rocks of Brittany. 
* See M. Burmeister’s excellent new work on Trilobites, which has already obtained high commenda- 
tion from distinguished naturalists. 
5 See Mr. Murchison’s description of the Devonian rocks in the Boulonnais. Bull. Soc. Geol. Fr., 
vol. viii. 
