Ostracods from the Upper Silurian of the Southern Baltic region

The Upper Silurian deposits in the southern Baltic region are represented by marine carbonaceous rocks and are subdivided into the Birštonas Beds of the Lower Ludlovian, the Pagegiai Beds of the Upper Ludlovian, and the Minija-Jura Beds of the Downtonian. The Birštonas Beds consist of clayey marls and dolomitic limestones. The thickness of the deposits reaches 101.2 m. The Birštonas strata are characterized by the following ostracods: Craspedobolbina robusta Mart., Pseudobollia krekenavensis Neck., Microcheilinella malinowieckaja Neck., Rectalloides aequalis (Neck.), Bairdiocypris venustas Abushik (nonem nudum), and Silenis subtriangulatus Neck. The ostracods Pseudoaparchites gregarias (Sarv) and Amygdalella nasuta Mart., which widespread in the upper part of the Birštonas Beds, arc also met with in the younger Pagegiai Beds. From the Birštonas Beds a new species, Microcheilinella formosa n. sp., is described. The Pagegiai Beds consist of interstratified clayey limestones and marls. The thickness of this unit is 73.5 m. In the Pagegiai Beds the following ostracods have been found: Ochesaarina variolous Neck., Primitiopsis ezerensis Gail., Craspedolobina percurrens Mart., Neobeyrichia ctenophora Mart., and Pseudorayella scala Neck. The ostracods Saccelatia bimarginata Neck., Clavofabella reliqua Gail., and Hebellum trivialis Gail. are met with in both the Pagegiai and the Minija Beds. Cavellina insueta n. sp. and Healdianella piriformis n. sp. are described. The calcareous-argillaceous formations of the Downtoman Series are subdivided into the Minija and Jura Beds. The thickness of these deposits is 195.2 m. They are characterized by the ostracods Borussulus reticulifer Mart., Amygdalella subclusa Mart., A. solida (Gail.), A. recta (Gail.), Scipionis profundigenus Mart., S. amplus Gail., Sleia equestris Mart., S. inermis Mart., Hemsiella dalmaniana (Jones), Macrypsilon salterianum (Jones), Neobeyrichia buchiana (Jones), N. alia Gail., N. incerta Gail., Cavellina angulata Neck., and C. circuiala Neck. From the Minija Beds, Cavellina transitiva n. sp. is described.