MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND
91
+ Hauerina compressa d'Orbigny, 1846
(PI. XVIII, Fig. 7a, b)
1846. Hauerina compressa d'Orbigny; A. d'Orbigny, p. 119, PI. 5, Figs 25-27.
1955. Hauerina compressa d'Orbigny; M. J. Serova, p. 330, PI. 14, Figs 1-3.
Material. - 20 specimens (ColI. No. F-142).
Dimensions: L ~ 0.68; B ~ 0.57; T ~ 0.15.
Description. - Test nearly circular, flat, in the central part concave;
periphery subacute or acute; chambers slightly inflated, narrow and
elongate, 3-4 in the last whorl, arranged planispirally around the previous
chambers, two to a whorl, and covering the initial part which is indistinctly
visible in the center of the test; sutures arcuate, bent backwards, depressed;
surface smooth and polished, slightly transparent; aperture as a narrow,
oval, inflated trematophore composed of about 12 fairly large irregular
pores.
Variability and ontogeny. The juvenile specimens have two chambers
to a whorl and their aperture is narrow with a long simple tooth, as in
Spirosigmoilina. Later the chambers grow shorter and shorter, up to four
to a whorl, as in typical specimens, and the aperture becomes
trematophore.
Remarks. - In comparison with the typical forms of d'Orbigny, our
specimens are more flattened, they have nearly foliaceous test shape and
resemble Hauerina jragilissima (Brady), Recent. The specimens found in
the material of the same age from Buitur in Romania are similarly
flattened, but only occasional specimens show somewhat inflated walls,
as figured by d'Orbigny. The species under study differs from H. jragilissima
(Brady) in the more oval shape of the juvenile stage, in the presence
of more then two chambers to a whorl in the mature stage, and in that
its test is less flattened. From H. bradyi Cushman, Recent, it differs
in its smooth, nor striated surface and in the less flattened test. From
H. atlantica Cushman, Recent, it differs in the less inflated and more
regular chambers.
Distribution. - Poland: Upper Tortonian (Gliwice Stare, W~glinek).
Austria: the vicinity of Vienna. Romania: Tortonian, Buitur. USSR: Upper
Tortonian, the Volhyn-Podolian Platform.
Hauerina plana Serova, 1955
(PI. XVIII, Figs la, b, 2a, b)
1955. Hauerina plana Serova; M. J. Serova, p. 331, PI. 14, Figs 4-6.
Material. - 30 specimens (ColI. No. F-144).
Dimensions: L ~ 0.35; B ~ 0.30; T ~ 0.12.
Description. - Test oval, much flattened, periphery subacute; outer