Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 73. (Budapest 1981)

Vörös, A.: A survey of the Rhaetian (Upper Triassic) Bivalvia from Borzavár (Bakony Mts., Hungary)

Genus CERCOMYA AGASSIZ, 1843 Cercomya ? zannoni (STOPPANI, 1863) (Plate II: 12) 71861: Anatina ? praecursor, QUENSTEDT—

MOORE, Avicula contorta Zone, p. 507, pl. XVI, fig. 3. *1863: Anatina Zannoni STOPPANI, Couches à Avicula.

.., p. 127, pi. 29, fig. 23. 71962: Laternula zannonii (STOPPANI) 1860—65 — ALASSINAZ, Retico Endine, p. 358, pl. XXV, fig. 15-16. 71963: Laternula zannonii (STOPPANI) 1860—65 — BELLONI, M. Torrezzo, p. 419, pl. XXVII, fig. 15. 1968: Laternula zannonii (STOPPANI, 1860—65) — SIRNA, M. Amelia, p. 784, pi. 56, fig. 1, 6, 7 (7). Material : 2 internal casts. — Locality : Borzavár, Rhaetian yellow limestones. D i m e n s i o n s (mm): length: 16.5 16.4 height: 11.0 10.0 Description : The specimen is of small size for the genus; moderately inflated. The outline is elongate, subelliptical, inequilateral. The posterodorsal margin is straight; the posterior margin is nearly vertical, tends to be truncated but its delimiting corners are not sharp. The ventral margin is widely, the anterior one is narrowly arched. The anterodorsal margin shows a weak sinus just before the umbo. The umbo is situated anteriorly, pointed. An ill-defined diagonal ridge runs from the umbo to the posteroventral corner. The surface of the internal cast is covered with weak, irregularly spaced growth lines. Remarks : The original figure by STOPPANI (1. c.) and especially the photographs by SIRNA (1. c.) excellently demonstrate this species. The specimen figured by MOORE (1. c.) under the name "praecursor" seems to belong here and not to C. rhaetica (GÜMBEL, 1861) as suggested by DITTMAR (1864, p. 186). This view is supported by the more prominent umbo, the convergent dorsal and ventral margins and by the presence of "a slight area on the posterior dorsal margin" (MOORE, I.e., p.

507). According to the concept of the "Treatise" (Cox et al. 1969) the genus Laternula has a fossil record from the Late Cretaceous to the Present, therefore our Triassic species can not be assigned to it. The genus Cercomya is the only member of the family Laternulidae which lived in the Late Triassic. Distribution : Rhaetian of the British Isles (7), the Southern Alps, the Central Apennines and the Bakony Mts. (Hungary). References ALASSINAZ, A. (1962): II Trias in Lombardia (Studi geologici e paleontologici). III. Studio paleontologico e biostratigrafico del Retico dei dintorni di Endine (Bergamo) (1). — Riv. Ital. Paleont., 68 (3): 307-376. ALASSINAZ, A. (1972): Revisione dei Pettinidi triassici. — Riv. Ital. Paleont., 78 (2): 189-428. BELLONI, S. (1963): La série retica del Monte Torrezzo (Val Cavallina) (1). — Riv. Ital. Paleont., 69 (3): 385-426. BENECKE, E. (1900): Myophoria inflata Emmr. im schwäbischen Rhät. — TV. Jb. Min. Geol. Pal, (1900)(1): 218-224. BERTULETTI, C. (1962) : Studi paleontologici sul Lias del Monte Albenza (Bergamo). I. Lamellibranchi dell'Hettangiano. — Riv. Ital. Paleont., 68 (2): 169-192. BiTTNER, A. (1912): Lamellibranchiaten aus der Trias des Bakonyer Waldes. — In: Resultate der Wissenschaftlichen Erforschung des Balatonsees, 1 (1) Anhang: Palaeontologie der Umgebung des Balatonsees., 2 (3): 1-107. BÖCKH J. & LOCZY L. (1912) : Einige rhätische Versteinerungen aus der Gegend von Reziim Komitat Zala und das Resultat neuerer dortiger Aufsammlungen. — In: Resultate.

.. etc. (as above), 2(7): 1-8. CAPELLINI, G. (1866): Fossili infraliassici dei dintorni del Golfo della Spezia. •— Mem. Accad. Sei. Ist. Bologna, (2) 5: 1-101. Cox, L. R., NEWELL, N. D., BRANSON, C. C, CASEY, R., CHAVAN, A. & al. (1969): Systematic descriptions. — In. : MOORE, R. C. (Ed). : Treatise on Invertebrate paloentology. Part N. : Bivalvia. : N225-N868. 4 Természettudományi Múzeum Évkönyve 1981