MILIOLIDAE - Acta Palaeontologica Polonica

122 EWA LUCZKOWSKA
Pyrgoella globiformis (Karrer, 1867)
(PI. XXI, Fig. 7a, b)
1867. Biloculina globiformis Karrer; F. Karrer, p. 357, PI. 2, Fig. la-c.
Material. - About 50 specimens (ColI. No. F-175).
Dimensions: L 0.55-0.9; B 0.55-0.8; T 0.55-0.8.
Description. - Test nearly spherical; last chamber large and inflated,
embracing those of preceding whorls, so that the penultimate chamber is
visible beneath the aperture only as an oval trace tapering at the base;
sutures indistinct; aperture large, semicircular, at the top of a small
extension of the last chamber, with a small semicircular, arcuately bent
tooth or without tooth.
Variability. The spherical test shape may be sometimes irregular,
i.e. the last chamber may be more or less inflated laterally. The tooth may
be semicircular or triangular in shape, or it may be partly or entirely
reduced. A peculiar feature of the species is the weak junction of chambers,
which, as a result, disintegrate readily.
Remarks. - This species differs from Recent Pyrgoella sphaera (d'Orbigny)
in having a semicircular aperture and tooth, not modified by
supplementary opening. From P. globulus (Bornemann) from the Oligocene
it differs in the semicircular aperture, somewhat projecting above the
surface and in the elliptical not circular, penultimate chamber.
Distribution. - Poland: Tortonian (Gliwice Stare, Karsy, Korytnica,
W~glinek). USSR: Neogene, West Ukraine, Holubica near Pieniaky.
X Pyrgoella ventruosa (Reuss, 1867)
(PI. XXI, Figs la, b, 2a, b, 3; Text-fig. 39/3)
1867. Biloculina ventruosa Reuss; A. E. Reuss, p. 69, PI. 1, Fig. 9.
1877. Biloculina grinzingensis Karrer; F. Karrer, p. 375, PI. 16a, Fig. 8.
1898. Biloculina dokiCi Pavlovic; P. S. Pavlovic, p. 122, Figs 1-3 (in Catalogue
Ellis & Messina).
Material. - 30 specimens (ColI. No. F-178, Sec. No. 410, 411).
Dimensions: L 0.7-1.3; B 0.55-1.1; T 0.6-1.3.
Description. - Test egg-shaped, circular-oval in cross-section, periphery
broadly rounded; chambers very broad, inflated, last chamber
embraces those of preceding whorls except the penultimate one, also
sometimes a very small trace of the third chamber is visible; sutures
indistinct, flat, with a wide border along the chamber edge; surface
smooth, polished; aperture semicircular or oval, high, open, with a semicircular
flap, which is depressed at the centre.
Dimorphism and ontogeny. The specimen sectioned belongs to the
mega I generation; PD 70 f.L. The internal structure is pseudotriloculine
initially, then biloculine (Text-fig. 39/3). The chamber shape in crosssection
semicircular in the early stage, becomes sickle-like later.