Folia Historico-Naturalia Musei Matraensis - A Mátra Múzeum Természetrajzi Közleményei 16. (1991)

Fűköh, L.: Examinations on faunal-history of the Hungarian holocene Mollusc fauna (Characterization of the succession phase)

III. Granaria frumentua zone We can observe newly the occurrence of species preferring open spaces and steppe beside the dominance of closed forest fauna, in the sediments (

Vallonia costata

, Granaria frumentum

, Aegopinella minor and sometimes Chondrula tridens

. Their relative frequency is around 30 \

. The low.er boundary of this zone is the renewed appearance of Granaria frumentum in the fauna. Its upper boundary is the minimum of steppe fauna. The stratotype can be found at

: Nagyoldali-shaft

, 6. sample. At the upper boundary of its zone we can observe the sudden decrease of steppe species) from 30 H to 15 \). Other localities are

: Szilvásvárad: Szalajka-valley 3.-4. samples, Mónosbél: calcareous tufa -mine, Kajla-bérc - cave 3. sample, Petényi-cave H3 sample. IV. Helicigona faustina zone The dominance of forest species is around 85 - 90 4, again. The composition of this fauna is similar to Clausili idae zone s. Characteristic species are Laciniaria biplicata

, Laciniaria plicata

, Clausilia pumila

, Ruthenica filograna. Here appears Helicigona faustina in the sediments for the first time. This species later will be general in recent faunas. The lower boundary of the zone is the change in dominancj ratios of the fauna. (The relative frequency of forest species is 85 - 90 \. (The upper boundary is the development of the recent fauna. Its stratotype is

: Kis-Kőháti-shaft A. sample. The sample can be correlated well with vertebrate stratigraphy. Other localities are

: Rigó-hole, Szentgál: the sediments of Кб-lik-cave, Nagyoldali-shaft 1.-3. samples, Szilvásvárad: Szalajka-val ley l.-3a samples, Mufloncave I. profile 1. sample, Csunya-valley the sediments of the third rock shelter, Kajla-bérc-cave 1.-2. samples. According to our knowledge there is no way for expanded correlation examinations in ranging the Mollusc fauna of Hungarian subsided zones like in case of the fauna of the medium high mountain ranges, but the characteristic species of the succession afford possibility for the description of biozones. I. Lithoglyphus naticoides - Valvata piscinalis zone The name of the zone is given by the two characteristic species of it. Among them we have to emphasize Valvata piscinalis in view of its relative frequency (80-85 '-,). The lower boundary of the zone is the appearance of fauna free from Pleistocene species. The upper boundary is the strong decreasing or accidental disappearing of Valvata piscinalis (Sárrét S1.IDB-L sample. Its stratotype is

: Fejér county, Sárszentmihály I. (A-I.) C-2 samples. II. Gyraulus albus - Bithynia tentaculata zone The zone is named after the characteristic species of the fauna. The dominance of Bithynia tentaculata decreases significantly, or sometimes disappeares from the fauna at the upper boundary of the zone. Among the faunas of the examined territories the relative frequency of Gyraulus albus is 55 - 60 4 Sárrét SI. II./A - 3 - II./B - 2 samples III. - 1 - III. - 3. Stratotype : Fejér-county, Sárrét, Sárszentmihály, I. locality, II./A - 1 III.-2 samples. III. Bithynia leachi - Gyraulus riparius zone Gyraulus riparius appears in these sediment s fauna at first time, here. And disappeares again at the upper boundary of the zone. Bithynia leachi reaches its maximum here, replacing the previous dominant species, the Bithynia tentaculata

. Its stratotype is

: Fejér-county, Sárrét, Sárszentmihály, I. Ill - 3 - IV/B 2 samples. 22