MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND
151
Genus Nummoloculina Steinmann, 1881
X + Nummoloculina contraria (d'Orbigny, 1846)
(PI. xv, Figs 5a-c, 6a, b; Text-fig. 53/1, 2)
1846. Biloculina contTaTia d'Orbigny; A. d'Orbigny, p. 266, PI. 16, Figs 4-6.
1881. Nummoloculina contTaTia (d'Orbigny); G. Steinmann, p. 31, PI. 2, Figs 1-8.
1951. Nummoloculina contraTia (d'Orbigny); P. Marks, p. 40.
1958. Nummoloculina contTaTia (d'Orbigny); I. V. Venglinsky, p. 65, PI. 7, Figs 4, 5.
Material. - Over 50 specimens (ColI. No. F-201, Sec. No. 424, 425, 432).
Dimensions: L 0.5-1.65; B 0.45-1.55; T 0.3-0.7
Description. - Test large, robust, circular, flat, periphery rounded;
chambers broad, flat, 2-5 in the last whorl, covering those of the preceding
whorls entirely; sutures very lightly depressed, arcuate, sometimes
S-shaped, irregular; wall thick; surface smooth, polished; aperture large,
semicircular or triangular, filled with semicircular or triangular flap.
Variability. The characteristic features of this species are stable, only
the number of chambers in the last whorl is variable.
Dimorphism and ontogeny. The sections show chambers strongly
increasing in size, the sides of which entirely cover all the preceding
chambers except the periphery of the penultimate one (Text-fig. 53/1,2).
In the juvenile stage of the micro generption a turn of the coiling axis
occurs after 2-3 chambers have been built; another turn, back to the
previous position, follows the creation of the next 6 chambers. The turn
of coiling axis in the ontogeny of the mega I generation is less distinct;
PD: micro - 2011, mega I - 70 ~. The large specimens belong probably
to the micro generation, the small ones - to the mega I generation.
Remarks. - Wiesner, 1923 (fide Barker, 1960) considered Planispirina
sigmoidea Brady, 1884, the type species of the genus Sigmoilina, to be
a synonym of Nummoloculina contraria (d'Orbigny). Thus the genus
Sigmoilina became a synonym of the genus Nummoloculina. It seems
however, that Planispirina sigmoidea does not belong to the species
Nummoloculina contraria, though it is a juvenile stage of Nummoloculina.
It is very similar to Nummoloculina circumcostata Margerel, from the
Pliocene of France but differs in the lack of a distinct border near the
periphery and in a flat, not convex central part of the test.
Distribution. - Poland: Tortonian (Brzeznica, Gliwice Stare, Grzyb6w,
Krywald, Ligota Zabrska, Rybnica, Wieliczka). Austria: Tortonian, Baden,
Vienna Basin. Czechoslovakia: Tortonian, Devinska Nova Ves, Zidlochovice.
Genus Spirosigmoilina Parr, 1942
+ Spirosigmoilina crenata (Karrer, 1868)
(PI. XVII, Figs 15a, b. l6a, b; Text-fig. 53/5)
1868. Spiroloculina CTenata Karrer; F. Karrer, p. 135, PI. 1, Fig. 9.
1917. Massilina CTenata (Karrer); J. A. Cushmann, p. 57, PI. 20, Fig. 2a, b.