Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 18. 1996. (Budapest, 1996)

FRAGMENTA MINERALOGICA ET PALAEONTOLOGICA 18. BUDAPEST, 1996 p. 71-78 Anterior fringe fragment of Clavagella (Bivalvia) from the Middle Miocene (Badenian) sandy deposits of Szob (Börzsöny Mts., Hungary) by A. Dulai DULAI, A. (1996): Anterior fringe fragment of Clavagella (Bivalvia) from the Middle Miocene (Badenian) sandy deposits of Szob (Börzsöny Mts., Hungary). - Fragm. Min. et Pal., 18: 71-78. Abstract: A small fragment of anterior fringe of Clavagella (Stirpulina) was collected from the Middle Miocene sandy deposits of Szob. This is a new element of the very rich mollusc fauna of the locality. The mode of life and the ecological characters of the so-called tube-dweller clavagellacean bivalves are briefly discussed. INTRODUCTION Szob is one of the most famous Miocene localities of Hungary, at the SW slopes of the Börzsöny Mountains at the northern border of Hungary (Fig. 1). The main mass of the mountains consists of volcanic rocks; sedimentary formations are only at the margins of the mountains. The Early Badenian andésite is overlain by, also Early Badenian, Leitha Limestone (BÁLDI & KÓKAY 1970) and some other sedimentary rocks, including the examined sands of Szob. The old sandpit is NW of Szob on the left bank of the Ipoly River. The fossils of the yellowish-grey sand were already studied from the mid nineteenth century, owing to the rich mollusc fauna. After several smaller papers, the mollusc fauna was examined in detail by CSEPREGHY-MEZNERICS (1956); in her monograph 267 gastropod and 74 bivalve species were listed and 143 of them were briefly described. MATERIAL Recently a paleoecological work was made on the described bivalves, which can be found in Hungarian Natural History Museum, Budapest (DULAI, in press). As this material was collected by several people during a century between 1848 and 1952, the taxonomic composition of this collection may not be very representative for the locality. For this reason a new collection was made by the author. This second material is derived from the coarse fraction of 10-12 kilogram washed sand collected from the locality. The taxonomic composition and the ecological characters of the two collections were compared (DULAI, in press).