MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 129
wrinkles (PI. XXV, Fig. 4). The juvenile specimens are narrowly oval in
shape, the last chamber being somewhat protruded upwards.
Dimorphism and ontogeny. The section show the micro generation;
PD 40 J1. The internal structure is cryptoquinqueloculine, the juvenile
stage being sometimes irregularly quinqueloculine (Text-fig. 43/1). The
lmm
c1@)b @2b ~b ~
~~,~,@'.,
Fig. 43. Ontogeny and internal structure of Sinuloculina; 1 S. micTodon (Reuss).
Upper Tortonian, Gliwice Stare, micro generation; 2-4 - S. nitens (Reuss), Upper
Tortonian, Gliwice Stare, micro generation; 2 -form with extension of last chamber.
3 - typical form, 4 - form without extension of last chamber; a front view, b apertural
view, c cross-section.
juvenile stage, obtained from the inside of an adult by the removal of the
last chambers, is a very narrow and slender specimen, resembling
Sinuloculina consobrina (d'Orbigny) (Part I, Text-fig. 10).
Remarks. - The juvenile stage obtained from the inside of the test
differs from Sinuloculina consobrina (d'Orbigny) in having a characteristic
slender shape. It differs from S. nitens (Reuss) in the less slender test
shape and the chambers bent distinctly at the base. Adult specimens
resemble Sinuloculina laevigata (d'Orbigny) in their quadrangular test
shape, differ however in distinctly elongated and more flattened test and
in the less inflated lower part of chambers. The single specimen of
S. microdon, found in the comparative materials from Voslau, is similar
to our form; compared with our forms, both this specimen and that
9 Acta Palaeontologica nr 117t