Twenty two species of Jurassic R udistae (induding 11 new ones) have been described from the margin of the Holy Cross Mountains (Góry Świętokrzyskie). A new genus Macrodiceras has also been erected. Conditions of asymmetry among the Rudistae have been discussed and their presumable causes analyzed. The influence exerted by ecological-facial factors on the development of the Rudistae has also been presented. Problems of the phylogeny of the Rudistae and their stratigraphic importance are discussed. The growth changes of shells in some species are described.