Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 50. (Budapest 1958)

M. Nyírő, R.: The studying of Foraminifera in thin sections

Its chambers are oval, the apertures between the chambers are well visible. The initial chamber is circular also in this genus. Number of chambers visible in cuts : 20—21. Clavulinoides szabói (Hantk.) Plate figs. 3a-b-c Its section shows a cone-like shape. The triserial structure of the older chambers are well discernible. Upon these the younger, uniserial chambers are budt. The characteristical, tubuliform aperture can be seen only on the youngest chamber. The younger chambers are built lobately onto the smaller, older chambers. The material of the test is agglutinated from relatively finer mineral grains. Number of chambers : 18—19. I present the thin section picture of Clavulinoides szabói (Hantk.) shown by Hagn in figure 3 c. There is a rather big difference between the specimens shown by the above author and mine. As is to be seen on the figure (3 c), the shape is less like a cone, its chambers are not even, and it is more roughly arenaceous. Number of chambers : 16. One may assume that the specimens introduced by Hagn is, at the best, a variation of szabói, but not a typical szabói. I have made the thin sectioning of the above enumerated arenaceous tests. Though there are many similarities among the several species, indeed, genera, we still dispose of features which should demand the separation of species and genera, even on the base of thin sections. In the followings, I introduce some calcareous forms. Robulus inornatus (d'Orb.) Plate figs, lla-b-c I present, in thin sections, a megalospheric (lib) and a microspheric (11c) form. The initial chamber of the megalospheric form is big, circular. The younger chambers are triangular. The separating walls are thick, similarly to the external wall. Number of whorls : 3. Number of chambers : 10—12. In the microspheric form, the initial chamber is also a sphere, yet very small. The younger chambers are bigger than the older ones. It has more whorls than the megalospheric form, namely 5. The number of chambers is also higher : 19—20. The walls are also thick. The aperture characteristical of Rubulus is well visible on the external wall, at every chamber. It shows no relationship with any of the involuted forms described up to now. Its thin section picture resembles the best the section of Epislommina pacrtshiana (d'Orb.). Marginulina fragaria Gümb. Plate figs. 8a-b The younger chambers are broadening, uniserial, whilst the older ones are involuted. It is a smaller and broader form than gladius. The characteristical ornamentation of the test disappears in the section. The initial chamber is circular.