Flabellamminopsis. Nowy rodzaj otwornic aglutynujących z doggeru okolic Częstochowy

Jerzy Małecki


Flabellamminopsis. New genus of agglutinated foraminifera from the Dogger in the vicinity of Częstochowa

Autor stwierdził i opisał nowe gatunki otwornic aglutynujących ze środkowo-jurajskich iłów rudonośnych z jury krakowsko-wieluńskiej i zaliczył je do nowego rodzaju Flabellamminopsis, utworzonego w obrębie rodziny Lituolidae.

In ore-bearing clays from the vicinity of Częstochowa, in the Parkinsonia parkinsonii and Parkinsonia compressa horizons, the author discover red previously unknown agglutinated foraminifers, similar externally to foraminifers of the genera Flabellammina and Frankeina, described by Cushman and Alexander, and occurring in the Cretaceous of North America. Carrying out a comparison of the Cretaceous genera Flabellammina and Frankeina with specimens from the Middle Jurassic, the author determined that between them there exists a fundamental difference, consisting in the development of the chambers, which in Flabellammina and Frankeina are smooth, while in the author’s specimens they are labyrinthic. Such a characteristic property, which by means of transillumination is observable in all of the author’s Jurassic specimens, precludes their inclusion in the known genera Flabellammina and Frankeina. Therefore, within the family Lituolidae the author creates the new genus Flabellamminopsis, and within the latter: new species and varieties. Among his specimens, more than 500 in number, the author distinguishes three fundamental forms: flat, tripterous, and tetrapterous. Apart from these fundamental shapes, numerously represented are intermediate forms which make it possible to arrange a full developmental series for the genus Flabellamminopsis. The building-material for the shells in this case are grains of sand, sharply angular and usually of one size, or fragments of shells of mollusks and calcareous foraminifers. Most authors are of the opinion that foraminifers are capable of selecting always the same material for constructing their shells, and on this basis they consider forms of identical shape but built of different material to be separate species. Consequently, following their example, the author of the present paper confers different specific names upon similar foraminifers of the genus Flabellamminopsis when they are built of different material.

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