MILIOLIDAE - Acta Palaeontologica Polonica

106 EWA l.UCZKOWSKA
Dimorphism and ontogeny. The sections show forms of the micro
generation, PD 10 fA. (Text-fig. 36/1) and mega I generation, PD 50-70 J.l
(Text-fig 36/2-5). The internal structure of the micro generation is
cryptoquinqueloculine initially, then pseudotriloculine, e.g. with one acute
and two obtuse (over 130°) angles, measured between the three last
chambers (Text-fig. 36/1). The mega I generation is cryptoquinqueloculine
throughout. There also exist specimens with four (PI. XX, Fig. 1) or even
five chambers visible from outside (PI. XX, Fig. 2).
Remarks. - This species differs from Miliolinella valvulaTis (Reuss) in
its more elongated test shape, thinner wall, and broader, transversely
contracted aperture.
Distribution. - Poland: Tortonian (Gliwice Stare, Grabki Duie, Karsy,
Korytnica, Krywald, Ligota Zabrska, Zrecze). Bulgaria: Tortonian, the
north-western and north-eastern regions of Bulgaria. Czechoslovakia:
Lower Tortonian, Zidlochowice. Romania: Tortonian, Kostej in Banat.
USSR: Lower Oligocene, West Siberia and Middle Asia; Middle Miocene,
West-Precaucasian region, Dagestan, Georgia, Abkhasia, Crimea; Lower
Tortonian, Volhyn-Podolia Platform.
X Miliolinella valvularis (Reuss, 1851)
(Pl. XX, Figs 4, 5; Text-fig. 37)
1851. Triloculina valvularis Reuss; A. E. Reuss, p. 85, Pl. 7, Fig. 56.
Material. - About 100 specimens (ColI. No. F-159, Sec. No. 285, 288,
294-296).
Dimensions: L 0.35-1.0; B 0.32-0.85; T 0.25-07.
Description. - Test regularly oval, periphery broadly rounded, crosssection
broadly oval or triangular-oval in outline; chambers broad, inflated,
slightly narrowing at both ends, middle chamber convex, oval or narrowly
oval with tapering ends, occupying one-third of the breadth of the front
side; sutures somewhat depressed, with longitudinal groove along the
chamber edges; surface smooth; wall thick; aperture semicircular or
slightly triangular, with sinuous border and tongue-shaped flap, the central
portion of which is slightly depressed.
Variability. The number of chambers visible from outside is variable,
three in typical specimens or two in non-typical ones in which the last
chambers embrace those of the previous whorls so that only a narrow
trace of the third chamber remains between them (PI. XX, Fig. 5a-c). The
aperture flap of such "pseudobiloculine" specimens is thickened and
convex, without a depression in the central part. The "pseudobiloculine"
specimens resemble Pyrgoella, but they never have chambers arranged
in a single plane.
Dimorphism and ontogeny. The specimens sectioned represent the
micro generation, PD 10 ~, and the mega I generation, PD 70-100 ~l. The