The publication in 1839 of Murchison's Silurian System incited Barrande to carry on systematic researches on the equivalent strata in Bohemia. For ten years (1840–1850) he made a detailed study of these rocks, engaging workmen specially to collect fossils, and in this way he obtained upwards of 3500 species of graptolites, brachiopoda, mollusca, trilobites and fishes. The first volume of his great work, Système silurien du centre de la Bohême (dealing with trilobites, several genera, including Deiphon, which he personally described), appeared in 1852; and from that date until 1881, he issued twenty-one quarto volumes of text and plates.