of Mgr. Martin Valent doctoral thesis Hyoliths of the Barrandian Area The submitted Ph.D. thesis summarizes recent information on comparatively poorly known group of invertebrates - the hyoliths. The first part of the thesis is composed by six main chapters focussed in detail on various aspects of hyoliths; major characteristics and ecology of hyoliths, progress in systematic of hyoliths, principles of hyolith classification, stratigraphical and palaeogeographical distribution of hyoliths, hyoliths within the Bohemian Massif and morphology of hyoliths. Up-to-date information has been included in all chapters. New data were published in five author's papers on hyolith colour patterns, systematics of hyoliths, pattern of palaeogeographic distribution and palaeoecologic interactions between hyoliths and various elements of the Cambrian invertebrate fauna. Short appendage consists of the Czech-English-Chinese terminological dictionary, simplifying study of Chinese literature.