O niektórych gatunkach z rodzaju Bolboforma (Protozoa?) w miocenie Polski

Abstract

ON SOME SPECIES OF THE GENUS BOLBOFORMA (PROTOZOA?) FROM THE MIOCENE OFPOLANDSummaryIn the course of a micropalaeontological analysis of samples from the area of Kików (Miocene M3, periphery of the Góry Świętokrzyskie), interesting specimens of the genus Bolboforma D a n i e 1 s  et S p i e g 1 e r were encountered in rich and varied foraminifer material. Specimens of this genus were found for the first time in Upper Oligocene and Miocene rocks in the vicinity ofHamburg (The Federal Republic of Germany). Eleven species of this new genus, referred tentatively to the Protozoa, were described at that time; they were characterized by varied sculpture of the tests while the dimensions ranged from 120 to 170 micra.In the present article, the author discusses the criteria on the basis of which the genus Bolboforma was distinguished and points to a certain relationship between this genus and the facies. Two species, Bolboforma metzmacheri (C l o d i u s) and Bolboforma sp. aff. rotunda D a n i e l s  et S p i e g 1 e r, were found in the clayey deposits from Kików (Plates I and II). Bolboforma metzmacheri was previously described from the Middle and Upper Miocene in the area ofHamburg andBolboforma rotunda from the Lower Miocene and Upper Oligocene of the same area. Bolboforma sp. aff. rotunda differs from Bolboforma rotunda in the lack of a distinct apertural neck but the morphology of the test is identical. Bolboforma metzmacheri belongs to those Bolboforma in which the aboral face is flattened. According to the creators of the new genus, specimens with flattened aboral faces occur in younger deposits than Bolboforma with quite spherical tests, such as Bolboforma sp. aff. rotunda, described by the present author. Thus, it is an interesting fact that in the sampled material from Kików spherical forms occur together with those which are characterized by flattened aboral faces. It should be noted, too, that the Bolboforma from the Kików area occur together with a foraminiferal assemblage which is very similar to that from the Federal Republic of Germany. The facies of the deposits in Kików is also similar to that in the area of Hamburg, from which Bolboforma were described for the first time.