MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 93
Descriptions. - Test quadrangular-circular, thick, broadly oval in
cross-section, periphery rounded; chambers broad, inflated, irregular,
slightly overhanging, 3-4 in the last whorl; sutures depressed, slightly
bent to the back; surface smooth, polished; aperture large, semicircular,
with numerous small pores of different shape and dimensions.
Variability. The shape of the test is very variable as the structure of
chambers is so irregular that practically each specimen is somewhat
different.
Remarks. - This species differs from Hauerina composita Serova in
its more inflated compact test, not flattened in the central part.
Distribution. - Poland: Tortonian (Gliwice Stare, Korytnica, Niskowa,
W~glinek). USSR: Upper Tortonian, the Volhyn-Podolian Platform.
Genus Lachlanella Vella, 1957, emend. Luczkowska, 1972
Lachlanella incrassata (Karrer, 1868)
(pI. X, Figs 2a-c, 3a-c; Text-fig. 33/1, 2)
1868. QuinquelocuHna incrassata Karrer; F. Karrer, p. 148, PI. 2, Fig. 10.
Material. - About 200 specimens (ColI. No. F-147, Sec. No. 90-94).
Dimensions: L - 1.0-1.25; B - 0.6-0.85; T - 0.4-0.55.
Description. - Test oval, occasionally slightly tapering at both ends,
periphery angular, trapezoid in cross-section; chambers flat, narrow,~
arcuate, last chamber somewhat enlarged near the aperture; middle
chamber large prominent and broad, fifth chamber distinct; sutures flat,
distinct; surface covered with fine striae, which are slightly oblique and
bifurcated at the periphery, disappearing on chamber sides, where they
leave irregular traces only; wall thin; aperture narrow, high, somewhat
oblique to the periphery, surrounded with a slightly thickened edge and
with a narrow long tooth a little bifurcated at the end.
Variability. The test shape is generally constant, except the periphery,
which is occasionally rounded, and not angular (Text-fig. 33/1).
Dimorphism and ontogeny. The specimens sectioned represent the
micro (?) generation; PD 50-60ft. The sections show the juvenile stage
with 5-6 chambers, which are rounded in outline. It is only the succeding
chambers that become trapezoid, the roundedness of the edges being
variable in the course of ontogeny.
Remarks. - The specimens investigated differ somewhat from the
specimen figured by Karrer in having a less angular periphery and
somewhat oblique striae. The test ornamentation resembles that of Quinqueloculina
striolata Reuss, which has similar bifurcated longitudinal
striae, but its periphery is not angulate. Lachlanella nussdorfensis (d'Orbigny)
differs in the more elongated slender test shape and in having
fewer costae.