Original paper

Remarks on the shell structure of Halkyardia maxima Cimerman: its umbilical plug and the microspheric form

Cimerman, Franc; Košir, Adrijan


The paper presents for the first time the structure of the microspheric form of Halkyardia maxima in axial and equatorial thin-section photomicrographs. A very small proloculus (10 μm in diameter) is followed by a spiral composed of 9 chambers, gradually increasing in size. The axial section of the megalospheric form shows that the umbilical plug is not a special morphological formation but results from the accretion of lamellae of consecutive cycles.


microspheric formoligocenepaleogenehalkyardiasloveniaforaminifera