MILIOLIDAE - Acta Palaeontologica Polonica

MILIOLIDAE FROM MIOCENE OF POLAND 85
ticulata has a more slender shape, more depressed sutures and fewel, less
oblique and more prominent costae (7-10 on the middle chamber), which
intersect on both the sides and the periphery, producing a reticulate
ornament on them. The two species are closely related but they are easy
to distinguish.
Distribution. - Poland: Lower Tortonian (Benczyn, Karsy, Korytnica).
Austria: Tortonian, Forchtenau, Vienna Basin. Czechoslovakia: Lower
Tortonian, Zidlochovice. Romania: Tortonian, Buitur.
Cyclojorina stomata n.sp.
(PI. XIII, Fig. 5a-c; Text-fig. 27/1)
Ho!otypus: PI. XIII, Fig. 5a-c.
Locus typicus: Bore-hole Budy-l near Stasz6w, depth 212.7-212.8 m.
Stratum typicum: Lower Sarmatian, Syndesmya clays
Derivatio nominis: stoma - mouth, aperture: having a large distinctive aperture.
Diagnosis: Test oval, smooth with tubular chambers and broad sutures and with
a characteristic large circular aperture with a short bifid tooth.
Material. - About 500 specimens, (ColI. No. F-136, Sec. No. 360, 361).
Dimensions: Holotype length 0.5 mm; breadth 0.34 mm; thickness
0.23 mm; Paratypes length 0.48-0.58 mm; breadth 0.24-0.35 mm; thickness
0.14-0.24 mm.
Description. - Test oval to narrowly oval, tapering at both ends,
periphery rounded; chambers tubular, of uniform width throughout,
middle chamber large and convex, fifth chamber narrow, occasionally
visible; sutures broad and slightly depressed; surface smooth, polished;
wall thin; aperture large, circular or semicircular, with a slightly sloping,
everted border and a short narrow or quadrate, slightly bifid tooth.
Variability. The species is very variable in respect of test shape, which
may be more or less elongated, the chambers being more or less inflated
and the tooth shape varying from narrow and simple to broad and nearly
quadrangular. The wall of some specimens that probably represent the
gerontic stage may be covered with longitudinal, irregular wrinkles as in
Varidentella sarmatica (Karrer). The aperture and tooth show distinct
intermediate characters to the genus Varidentella, the tooth being
shortened and enlarged and the aperture semicircular in some specimens.
Most specimens have a circular aperture and a narrow bifid tooth.
Dimorphism and ontogeny. The specimens sectioned belong to the
micro generation, the proloculus diameter is 30 ~' The regular quinqueloculine
internal structure and the stable rounded shape of the
chambers during the ontogeny are visible in cross-sections (Text-fig. 27/1).
Remarks. - This species much resembles Varidentella sarmatica (Karrer)
but differs in having a large circular aperture with an everted berder
and a narrow or quadrate bifid tooth. It differs from Varidentella latela-