Scanning electron microscopy of some recent and fossil nodosariid f oraminifera

Abstract

23 recent and fossil species representing 15 genera within the Nodosariacea have been studied with respect to lamellarity. All forms were found to be monolamellar. However, four different categories of the monolamellar construction pattern were found. Of these the ortho-monolamellar type has a one-layered chamber with an enveloping secondary lamella covering the earlier exposed shell. If the secondary lamella covers only part of the earlier exposed shell it is termed plesio-monolamellar while a lack of secondary lami­nation is called atelo-monolamellar. Multiple lamination in the septa covering also the eaiilier exposed shell parts is called poly-monolamellar. The microgranular layer in Jurassic forms is of diagenetic origin.