Wall Structures of Palaeotextulariid Foraminifers and Discussion of Microgranular Test Walls

Abstract

Investigations of the test wall structures of Upper Palaeozoic Palaeobigenerina geyeri and other palaeotextulariid foraminifers revealed that the outer layer of the wall, previously interpreted as being microgranular, is agglutinated. The inner layer is composed of equidimensional, rhombohedral crystals apparently arranged in elements perpendicular to the wall surface, which resembles hyaline radial test walls in structure. The walls are perforate and the pores are branched. A comparison of microgranular and agglutinated test walls shows that their distinction seems very artificial and that a reinvestigation is required.