CAMBRIAN ROCKS OF BOHEMIA. 
487 
mud thrown down in the Fig. 574 . 
same sea, on the borders of 
which the sands above men¬ 
tioned were accumulating. 
In some of these slaty rocks 
in Ireland, immediately op¬ 
posite Anglesea and Carnar¬ 
von, two species of fossils 
have been found, to which OUhamia radiata, Wicklow, 
the late Professor E. Forbes 
Fig. 575. gave the name of Oldhamia. The nature 
of these organisms is still a matter of dis¬ 
cussion among naturalists. 
Cambrian Rocks of Bohemia {Primordial 
zone of Barrande), —In the year 1846, as 
before stated, M. Joachim Barrande, after 
ten years’ exploration of Bohemia, and after 
collecting more than a thousand species of 
fossils, had ascertained the existence in that 
country of three distinct faunas below the 
Devonian. To his first fauna, which was old¬ 
er than any then known in this country, he 
gave the name ofEtageC; his two first stages 
A and B consisting of crystalline and meta- 
. . morphic rocks and unfossiliferous schists. 
Olanamia ayiUqua. ^ t i t 
Forbes. Wicklow, Ihis Etage C or primordial zone proved ai- 
ireiand. terwards to be the equivalent of those sub¬ 
divisions of the Cambrian groups which have been above 
described under the names of Menevian and Lingula Flags. 
The second fauna tallies with Murchison’s Lower Silurian, 
as originally defined by him wdien no fossils had been dis¬ 
covered below the Stiper-Stones. The third fauna agrees 
with the Upper Silurian of the same author. Barrande, 
without government assistance, had undertaken single- 
handed the geological survey of Bohemia, the fossils pre¬ 
viously obtained from that country having scarcely exceeded 
20 in number, whereas he had already acquired, in 1850, no 
less than 1100 species, namely, 250 crustaceans (chiefly Tri- 
lobites), 250 cephalopods, 160 gasteropods and pteropods, 130 
acephalous mollusks, 210 brachiopods, and 110 corals and 
other fossils. These numbers have since been almost dou¬ 
bled by subsequent investigations in the same country. 
In the primordial zone C, he discovered trilobites of the 
genera Paradoxides^ Conocoryphe^ PUipsocephalus^ Sao, Ari- 
onellus, Hydrocephalus^ and Agnostus, M. Barrande pointed 
out that these primordial trilobites have a peculiar facies of 
