Trilobites from the Czech Republic are among the most classic fossils of all.  Even in the time of Joachim Barrande, fossils and especially Czech trilobites were traded and exchanged.  Barrande described more than 3500 species of trilobites and other fossils from the Prague syncline. This fossil region is named after him as the Barrandian region. Czech trilobites are known from the Cambrian, Ordovician, Silurian and Devonian periods. In particular, the trilobites from the Middle Cambrian of the Jince Formation are world famous. The species Ellipsocephalus hoffi and Paradoxides gracilis are almost synonymous with the Middle Cambrian. The Czech Republic offers a variety of classical sites of paleontology.