MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 149
polished; wall thin; aperture small, circular, placed at the end of a short
neck and with a short and simple tooth.
Variability and ontogeny. The characteristic features of this species
are stable. The shape of juvenile specimens is narrow and slender (PI. XVI,
Fig. 3), while the mature specimens are broader and slightly rhomboid
(PI. XVI, Fig. 1). The sections show a sigmoiline chamber arrangement in
the juvenile stage, then the chambers are added in a single plane (Textfig.
53/3).
Remarks. - This species differs from Sigmoilinita tenuissima (Reuss)
from the Miocene of Wieliczka in having broader chambers with flattened
sides and a more rhomboid test. From S. tschokrakensis (Gerke) it differs
in a more numerous chambers with more flattened sides, and in rhomboidoval
shape. The forms investigated correspond morphologically to the
topotypes from Baden, Vienna Basin.
Distribution. - Poland: Tortonian (Benczyn, Brzozowa, Budy, Grabki
Duze, Grzyb6w, Gliwice Stare, Karsy, Korytnica, L~ki Dolne, Krywald,
Miechocin, Rytwiany, Wieliczka, Zrecze). Austria: Lower Tortonian, Baden,
Vienna Basin. Czechoslovakia: Lower Tortonian, Zidlochovice. USSR:
Miocene, Precaucasian region and Ukraine.
x + Sigmoilinita tenuissima (Reuss, 1867)
(PI. XVI, Figs 4-6)
1867. Spiroloculina tenuissima Reuss; A. E. Reuss, p. 71, PI. 1, Fig. 11.
1955. Sigmoilina tenuissima Reuss; M. J. Serova, p. 326, PI. 12, Figs 5, 6.
Material. - 70 specimens (ColI. No. F-198).
Dimensions: L 0.4-0.45; B 0.2-0.25; T 0.04
Description. - Test oval, rounded at the base and tapering towards
the aperture, flattened, periphery rounded; chambers tubular, narrow,
arranged in a single plane, 2-3 on each side of slightly oblique juvenile
stage; sutures slightly depressed, indistinct; wall thin, transparent; surface
smooth, polished; aperture small, circular, at the end of a short neck and
with a short, simple tooth.
Variability. The shape of the test is stable. The number of chambers
of the planispiral stage depends on the ontogeny.
Remarks. - This species, described from the Miocene in Wieliczka,
differs from Sigmoilinita tenuis (Czjzek) from Baden in having narrower,
tubular chambers, a more regular shape and fine, transparent wall. The
topotypes from Wieliczka are figured in Plate XVI, Figs. 4-6.
DiStribution. - Poland: Tortonian, (Wieliczka, Zglobice). Czechoslovakia:
Tortonian, Devinska Nova Ves. USSR: Tortonian, the Precarpathian
Foredeep.