Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 1994. Sectio Geographiae.(Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 21)
Dávid Árpád: Palaeo-occological and palaeo-pathological observations on upper oligocene molluscs (Eger, Hungary)
the shell of an Athleta r arispina (Lamarck). The zoarium is around the aperture of the gastropod. Presumably after the animal's destruction, the shell lay upwards with its mouth on the sea-bottom. It functioned as a firm basis for the Bryozoa larvae so that the colony could develop. The other side of the shell is bare and eroded. I have found a small Bryozoa-colony on the valve of an Ostrea cyathula (Lamarck), too. The occurrence of Bryozoas indicate shallow-water region. The encrusting species refer to agitated water (GÉCZY, B. 1985.) In my opinion, the Bryozoa-colonies in both cases, by reason of the colony's structure, and the thick walls and rounded aperture of the zoecia, belong to the Genus Electra. The author managed to observe charasteristic traces of boringbivalve (Teredo sp.). Teredo is especially adapted for wood boring. In this case drift wood were exavated by them. During the fossilization the organisms did not endure. But their borings were filled in and cemented by limonitic sand. The tubes are approximately 0,5 cm in diameter. Since the tubes wound by fits and starts in the former driftwood, presumably, great number of borers could be in it. It signs that the bivalves often had to go round each other. The driftwood itself mouldered and vanished already, only some coalified pieces remind us of the feeding and dwelling place of the former borer-bivalves. These organisms may occur in most of the fossil communities because of the transportation of the currents. Palaeopathological observations While investigating fossils I could observe traces of predatory snails. The activity of these gastropods can be qualified in two different ways: it can be a palaeopathological symptom form the viewpoint of the prey, and on the part of the gastropod it can be a feeding trace (TASNÁDI-KUBACSKA, A. I960.). I could study borings of predatory snails in case of species belonging to the Class Gastropoda, Scaphopoda, Bivalvia. The species are as follows: Gastropoda: Polinices catena helicina (Brocchi), Polinices josephinia olla (De Serres), Athleta rarispina (Lamarck), Turritella beyrichi (Hofmann s. str.) Turritella beyrichi percarinata (T.-Roth), Turritella venus margarethae (Gaäl), Natica millepunctata tigrina (Defrance), Turris duchasteli (Nyst), Hadriana egerensis (Gábor), 37
