Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 19. 2001. (Budapest, 2001)

LAGHI (1977). However, the detailed studies on the recent Lepidochitona dnerea (LINNAEUS) by KAAS & VAN BELLE (1981) showed the characteristic differences between the fossil and the recent species (see details at STUDENCKA & STUDENCKI 1988). Middendorßa caprearum (SCACCHI) was synonymyzed with Lepidochitona corrugata (REEVE) by KAAS & VAN BELLE (1981). This present-day species can also be separated from Lepidochitona lepida (REUSS), but the high degree of similarity refer to a close relationship between the two species (see MALATESTA 1962; STUDENCKA & STUDENCKI 1988). The determination of the fossil species within the genus Lepidochitona is highly problematic. In the case of isolated, (sometimes fragmentary) fossilized valves, it is almost impossible compare with the recent species. Therefore, the two Hungarian specimens are included into the fossil species established by REUSS, as other authors in the case of Middle Mocene specimens of Austria, Poland and Romania also did it Distribution — This species has hitherto been known from the Czech Republic (Rudoltice: REUSS 1860, SULC 1934); Romania, Transylvania (Costei and Lápugiu: SULC 1934); Hungary (Hidas: CSEPREGHY-MEZNERICS 1950); Italy (SACCO 1897) and Poland (Korytnica: BALUK 1971, 1984; Nawodzice and Rybnica: STUDENCKA & STUDENCKI 1988; Weglinek and Weglin: MACIOSZCZYK

1988). Order Acanthochitonida BERGENHAYN, 1930 Family Acanthochitonidae PlLSBRY, 1893 Genus Acanthocbitona GRAY, 1821 Acanthochitona faluniensis (ROCHEBRUNE, 1883) (Plate II: 1-3) 1860 Chiton (Acantbochites) fasäcularis L. var. — REUSS, pp. 260-261, pi. 8, figs. 4-6. 1883 Acantbochites Faluniensis ROCHEBRUNE — ROCHEBRUNE, pp. 60-61. 1934 Acanthochiton faluniensis ROCHEBRUNE — S>ULC, pp. 17-18, pl. 1, fig. 29; pi. 2, figs. 30-32. 1971 Acanthochitona faluniensis (ROCHEBRUNE) — BALUK, pp. 463-464, pi. 2, figs. 10-15. 1984 Acanthochitona faluniensis (ROCHEBRUNE) — BALUK, pp. 291-292, pi. 8, figs. 1-5. 1988 Acanthochitona faluniensis (ROCHEBRUNE) — STUDENCKA & STUDENCKI, p. 41, pi. 4, fig. 3. 1988 Acanthochitonafalunensis (ROCHEBRUNE) — MACIOSZCZYK, p. 55, pi. 3, figs. 8-9. Material — One head valve (borehole Szokolya-2, 92.7-93 m) (M.99.111). Measurements (mm): length width M.99.111 1.38 2.1 Description — The relatively thick valve is ornamented by closely spaced nodes. The nodes are low, dorsally flattened and round in outline. The arrangement of the nodes is irregular. Two or three pores can be seen on each nodes. The apex region of the head valve is smooth, without any nodes, but with some pores. The insertion plate of the head valve is cut by six slits, in the extension of which there are shallow grooves not reaching the boundary of the tegmentum. Remarks — The only head valve well corresponds to the published specimens from the Vienna and Korytnica Basin (see SULC 1934, pi. 2, fig. 32; BALUK 1971, pi. 2, figs. 10-11; BALUK 1984, pi. 8, figs. 1-2.). The Pseudoacanthochiton subgenus, established by SULC (1934) has been synonymized with Acanthochitona GRAY by SMITH (1960). LAGHI (1977) postulated that both the Korytnica specimens and the Vienna Basin specimens are conspecific with the Recent Acanthochitona communis (RlSSO). This statement was rejected by BALUK (1984), STUDENCKA & STUDENCKI (1988) and MACIOSZCZYK (1988) because the shape of the tegmentum of the intermediate and tail valves is cleady different at the two species. The Hungarian specimen has six slits on the insertion plate of the head valve, while BALUK (1971) mentioned 5 slits at the Korytnica specimens. Distribution — This species is very frequent in the Central Paratethys. It was mentioned from several localities of the Vienna Basin, Bohemia and Transylvania (Kaiinice, Rudoltice, Steinabrunn, Coçtei and Lápugiu; SULC 1934). The remains of this species can be found at several localities in Poland (Korytnica: BALUK 1971, 1984; Nawodzice and Rybnica: STUDENCKA & STUDENCKI 1988; Monastyrz and Miasteczko: JAKUBOWSKI & MUSIAL 1977; Trzesiny: JAKUBOWSKI & MUSIAL 1979; Wçglinek, Wçglin and Lychów. MACIOSZCZYK 1988). Acanthochitona faluniensis (ROCHEBRUNE) was also mentioned from Várpalota (Hungary) by STUDENCKA & STUDENCKI (1988). Explanation to Plate I 1-3 Lepidochitona lepida (REUSS, 1860); intermediate valve; Szokolya-2,

109-111.2 m; M.99.109. — 1: dorsal view, x 30; 2: dorsal view (detail of Plate I: 1), x 300; 3: dorsal view (detail of Plate I: 2), x 600. 4-6 Lepidochitona lepida (REUSS, 1860); intermediate valve; Szokolya-2, 92.7-93 m; M.99.110. — 4: dorsal view, x 39; 5: dorsal view (detail of Pl. I: 4), x 300; 6: dorsal view (detail of Plate I: 5), x 1200.