MILIOLIDAE - Acta Palaeontologica Polonica

46 EWA LUCZKOWSKA
broad and sloping, with distinct acute edge, fifth chamber visible as
a projecting band; MS rounded and flat, rhomboid in cross-section,
periphery acute; chambers very broad, inflated, two small middle
chambers form a small elevation; sutures distinct, flush; surface smooth,
polished; aperture oval, with thickened rim in adult specimens, parallel
to the periphery in massiline specimens and slightly oblique in quinqueloculine
specimens.
Variability. The morphological features of this species are, as a rule,
constant. There is only some variation in the sharpness of the edge and
in the presence of oblique folds, connected with the growth of the test,
on the sides or only edges of chambers in some specimens (Text-fig.
11/2,3).
Dimorphism. Specimens of the micro, mega I and mega II generations
are present. The micro generation is represented mainly by massiline
'mm
Fig. 12. Ontogeny of Quinqueloculina buchiana d'Orbigny, Lower Tortonian, Korytnica,
micro generation; 1,2 - MS, 3 - QS; a front view, b apertural view, c crosssection.
and large quinqueloculine forms (Text-fig. 12) the mega I generation
has the shape of small quinqueloculine forms (Text-fig. 13/2-5). The
mega II generation is rare, its size being usually greater than that of the
mega I generation (Text-fig. 13/1). The massiline forms are also uncommon