(8)
Zygodiscales (2)
Helicosphaeraceae (1)
Helicosphaera (4)
H. carteri group (10)
Helicosphaera inversa
Description: Like H. carteri but with large pores separated by prominent conjunct sub-horizontal bar usually with inverse orientation.
Remarks:
Range: NN19 to 21 (LAD low in NN21).