This special volume deals with a widely distributed group of crustaceans - the ostracods. Their calcareous, bivalved carapaces have a high fossilization potential and make them one of the main research topics of micropaleontology, especially with paleoecologic and biostratigraphic emphasis. In the Austrian Neogene ostracode research lasts more than 150 years but only few papers give reliable descriptions and illustrations. The present publication offers a comprehensive documentation of Middle Miocene, predominately shallow marine taxa and provides thereby the base for sound taxonomic placement. Intraspecific variability, sexual dimorphism and ontogenetic changes are taken into account and figured too. Detailed differential diagnoses and (paleo-)ecologic discussions make this volume a valuable source for future paleo-/biological and biostratigraphical investigations.