Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 71. (Budapest 1979)

Szabó, J.: Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part I.: Euomphalidae (Archaeogastropoda)

Table I. Locality Facies Age Sümeg: Mogyorósdomb Hierlatz-type lmst. ? Upper Sinemurian Szentgál: Tüzköveshegy Hierlatz limestone Raricostatum Zone Gombáspuszta Red. manganiferous lmst. Carixian, mainly ibex Zone Herend : Carixian, mainly ibex Zone Kisnyerges-árok Red, manganiferous lmst. Upper Sinemurian — Carixian Hárskút: Közöskúti-árok Red, manganiferous lmst. Ibex Zone Lókút: Red, manganiferous lmst. Kericser Hierlatz-type lmst. with mixed Obtusum to Ibex Zone fauna Hierlatz limestone Ibex — Stokesi Zone Red, crinoidal lmst. Spinatum Zone Büdöskútpuszta Pink limestone with siliceous Davoei — Margaritatus — sponge-spicules Spinatum Zone Középhát Pink limestone with siliceous Davoei — Spinatum — sponge-spicules Margaritatus Zone Lókúti-domb Red, cherty crinoid lmst. Davoei Zone Káváshegy Red. cherty crinoid lmst. Jamesoni and Davoei Zones Eplény: Red. cherty crinoid lmst. Manganese Mine Vertical fissure infilling Domerian Zirc: Bocskorhegy Grey and pink lmst. with Jamesoni — Margaritatus siliceous sponge-spicules Zone Tés: Hamuháza Red, crinoidal lmst. Pliensbachian Somhegypuszta: Red, crinoidal lmst. Somhegy Horizontal fissure infilling Humphriesianum —• Parkinand red manganiferous soni Zone limestone ward the "parabolic notch", with extended interspaces, which indicate a tension in this direction, generated by the extended mantle edge. The suture-to-suture "parabolic growth-line" is a result of the restoration of the normal direction of growth. The withrawal of the temporal mantle extensions was followed by an opposed decline of the spiral threads and a re-establishment of their original density. The growth-lines themselves are also run differently. When infilling the scars of the "notches" (i.e. the spines), the first growth-lines are similar to the "parabolic growth-lines", but angle them. Subsequently a series follows with increasing similarity to the form of the normal growth-lines. Approaching the next spine, the growth-lines become more and more proverse near the keels. This suggests that the here situated, spine secreting parts of the mantle edge was the place of the most intensive shell secretion. The mechanism of infilling corresponds actually to the way of damaged shell restoration, when the soft parts withdraw into the shell, and the mantle edge reaches the margin of the part to be completed. The growth-lines run firstly parallel to the damaged margin, then the normal direction of growth is restored. The shell secretion remained continuous, even without retardations during the growthstops in 72° intervals. In these case the inner and outer varices were formed, with soft parts withdrawal and multilayered shell secretion. This way of growth is not unique. It can be recognised in the majority of the Discohelix and Pentagonodiscus species, where the newly built shell parts join the previous parts roof-tile-like or lelescopically (Plate II: fig. 12). The bars 2 Természettudományi Múzeum Évkönyve 1979