
Parr II. Sucr.i.§ 2.) CAMBRIAN. 659 
consisting mainly of quartzose and schistose strata or quartzo-phyllades, 
and yielding remains of Paradoxides and Lingula. All these rocks have 
been greatly disturbed and are covered unconformably by Devonian and 
later formations.1 In the north-west of France a large tract of Paleozoic 
rocks spreads through Brittany and the west of Normandy. Recent 
researches have shown that in that region there is an old gneiss with 
overlying mica-schists followed by a mass of what used to be called 
“transition ” strata, which appear to contain representatives of Cambrian, 
Silurian, and Devonian deposits. ‘Towards the west of this region the 
' gneiss and mica-schist are succeeded by green silky talcose-schists (phyl- 
lades de Douarnenez) and then by 100 to 120 metres of conglomerate 
and red shale. These strata may be Cambrian. They are followed by 
a persistent group of white sandstone and shale with Scolithus linearis 
(Grés armoricain),2 which may be the basement zone of the Silurian 
system of the north-west of France. In the basin of Rennes considerable 
bands of limestone, sometimes magnesian, together with quartzites, 
conglomerates, and greywackes occur in the great series of Cambrian 
schists. ‘Traces of annelides and perhaps of Oldhamia occur in these 
strata, but no evidence of the true primordial zone with its characteristic 
trilobite fauna has yet been discovered. 
‘The classic researches of M. Barrande have given to the oldest fossil- 
iferous rocks of Bohemia an extraordinary interest. He has made 
known the existence there of a remarkable suite of organic remains 
representative of those which characterize the Cambrian rocks of Britain. 
At the base of the geological formations of that region lie the Archean 
gneisses already mentioned. These are overlaid by vast masses of schists, 
conglomerates, quartzites, slates, and igneous rocks, which have been 
more or less metamorphosed, and are singularly barren of organic 
remains, though some of them have yielded traces of annelides. They 
pass up into certain grey and green fissile shales, in which the earliest 
well-marked fossils occur. The organic contents of this Htage C or 
Primordial zone form what M. Barrande terms his primordial fauna, which 
contains 40 or more species, of which 27 are trilobites, belonging to the 
characteristic Cambrian genera—Paradowides (12), Agnosius (5), Conocoryphe 
(4), Ellipsocephalus (2), Hydrocephalus (2), Arionellus (1), Sao (1). Nota 
single species of any one of these genera, save Agnostus (of which four 
species appear in the second fauna), has been found by M. Barrande higher 
than his primordial zone. Among other organisms in this primordial fauna, 
the brachiopods are represented by two species (Orthis and Orbicula), the 
pteropods by five (Theca), and the echinoderms by five cystideans. 
North America.—Rocks corresponding in position and in the 
general character of their organic contents with the Cambrian formations 
of Europe have been recognized in different parts of the United States 
and Canada. They appear in Newfoundland, whence, ranging by Nova 
Scotia and New Brunswick, they enter Canada, the northern parts of 
New York, Vermont, and eastern Massachusetts. They rise again along 
the Appalachian ridge, in Wisconsin, Minnesota, Missouri, Arkansas, 
_ 1 Dewalque, “ Prodrome dune Description Géol. de la Belgique,’ 1868. Mourlon, 
_“Géologie de la Belgique,’ 1880. Gosselet, “ Esquisse Géol. du Nord de la France, 
_ &e.,” 1880. 
2 Barrois, Bull. Soc, Géol. France, v. (1877), p. 266. ; 
2 Tromelin et Lebesconte, Bull. Soc. Géol. France, iv. (1876), p. 583. Barrois, Op. 
eit. v. (1877), p. 267. 
a Uae 
