MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM· MIOCENE OF POLAND 115
penultimate chamber projecting above the surface; sutures distinct;
surface smooth, polished; aperture very broad, occasionally occupying the
whole breadth of the test, with a low and wide, tape-shaped tooth which
has lateral extensions at both sides.
Variability and ontogeny. The topotypes from Wieliczka show a very
variable aperture which may be small (PI. XXII, Figs 7, 8) or wide and
low (PI. XII, Fig. 6.). The convexity of chambers is also variable, for they
are sometimes more inflated basically, and then the lateral outline of
the test is S-shaped, as in Pyrgo inornata d'Orbigny. The specimens
sectioned belong to the micro generation; PD 10 J!. The internal structure
is initially irregularly triloculine, then biloculine. The juvenile triloculine
stage is very small in comparison with the biloculine stage (Text-fig. 39/2).
Fig. 39. Internal structure of Pyrgo and PyrgoeUa; 1 - Pyrgo truncata (Reuss), Lower
Tortonian, Wieliczka, micro generation; 2 - Pyrgo amphiconica (Reuss), Lower
Tortonian, Wieliczka, micro generation; 3 - PyrgoeUa ventruosa (Reuss), Lower
Tortonian, Wieliczka, mega I generation; 4 - Pyrgo clypeata (d'Orbigny), Lower Tortonian,
Karsy, mega I generation; 5, 6 - Pyrgo inornata (d'Orbigny), Upper Tortonian,
Gliwice Stare; 5 - micro generation, 6 - mega II generation; 7 - Pyrgo lunula
(d'Orbigny), Upper Tortonian, Gliwice Stare, mega I (?) generation; 8 - Pyrgo subsphaerica
(d'Orbigny), Upper Tortonian, Gliwice Stare, mega I (?) generation; 9­
Pyrgoella controversa (Bogdanowich), Upper Tortonian, Gliwice Stare, mega I generation.
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