MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 131
Austria. According to Reuss, it however differs in the bifid, not simple,
tooth in the aperture and in the more flattened sutures. The present investigation
shows that the difference between these two species given
by Reuss is not important, as both the characteristics of the aperture and
tooth and those of the sutures oscillate within the same limits in both
species. On the other hand, a true difference between them is the much
greater elongation of the test of S. nitens. The lengh/breadth ratio of the
specimen from Grinzing figured by Reuss is 2.7, that of our specimens
from Gliwice Stare 2.5-3.0, and these values calculated for S. consobrina
from Nussdorf and our specimens from W~glinek are, respectively, 2.4 and
about 2.2. In materials from Nussdorf, Voslau, Buitur and Lapugiu only
S. consobrina has been found, and therefore there is no certainty as to
what S. nitens is like. As the lengh/breadth ratio and morphology of
S. nitens correspond to those in our specimens, it has been decided to place
them in this species tentatively.
Distribution. - Poland: Upper Tortonian (Gieraszowice, Gliwice Stare,
Ligota Zabrska, W~glinek). Austria: Tortonian, vicinity of Vienna (Grinzing).
Czechoslovakia: Lower Tortonian, 2idlochovice. USSR: Upper
Tortonian, Volhyn-Podolian Platform and Black Sea Depression; Middle
Miocene, Caucasus; Meotian (Pliocene), Black Sea Depression.
X Sinuloculina rixatoria (Franzenau, 1890)
(Pl. XXIV, Fig. 5a-c; Text-fig. 44)
1890. Biloculina rixatoria Franzenau; A. Franzenau, p. 165, PI. 2, Fig. la-c.
Material. - About 100 specimens (ColI. No. F-183, Sec. No. 121-125)..
Dimensions: L 1.15-1.4; B 0.55-0.95; T 0.4-0.5.
Description. - Test narrowly oval, slender, tapering at both ends,
flattened, obliquely truncated at the top; periphery rounded; chambers
flat, broad, elongated, with a sinuous inner edge and the apertural end
occasionally slightly protruded; two chambers visible from outside; sutures
distinct, broad, with a narrow border marked along the chamber edges;
wall thin; surface smooth, dull; aperture circular, even with the periphery
or on a small extension of the chamber, surrounded with a thickened rim,
and with a large thick bifid tooth, which often projects above the aperture
border.
Variability. The test shape is variable, being more cylindrical in small
specimens and flattened and oval in section in large specimens. In rare
forms there is also a small narrow trace of the third chamber.
Dimorphism and ontogeny. The specimens sectioned belong to the
micro generation, PD 50 J!, and the mega I generation, PD about 130 J!.
The internal structure of juvenile stage is irregularlytriloculine, then
irregularly biloculine; opposite chambers embrace the preceding ones and