The brachiopod genera Hebertella, Dalmanella, and Heterorthina from the Ordovician of Kentucky

The orthid brachiopod genera Hebertella, Dalmanella, and Heterorthina are abundant in Middle and Upper Ordovician strata in Kentucky. 'Nine species are described: Hebertella frankfortensis Foerste; H. parksensis Foerste; H. occidentalis (Hall); Dalmanella bassleri Foerste; D. fertilis (Ulrich); D. meeki (Miller); D. multisecta (Meek); D. sulcata Cooper; and Heterorthina macfarlani Neuman. The species designations Hebertella sinuata (Hall), H. subjugata (Hall), and H. latasulcata Foerste are placed in synonymy with H. occidentalis (Hall). The stratigraphic distribution of each species is given. Large collections of silicified specimens allowed the recognition of the considerable variability characteristic of most of the species. External morphology distinguishes species of Hebertella, whereas internal features are critical to recognition of species of Dalmanella and Heterorthina.