print this page- Citation:H. recta group of Young (1998)
Distinctive group of Late Oligocene to Mid Miocene Helicosphaera species, with flange terminating abruptly rather than expanding into a wing. Blanket confined to central area, so flange is dark is dark in cross-polars. Central area openings usually show inverse orientation (i.e. they point toward the flange termination). Bar conjunct with rim.
Drawing Outline description Range 
H. recta - large pores separated by horizontal bar NP24-NN1 
H. obliqua - tear-drop shaped with narrow, distinctly oblique, openings
NP24-NN6 
H. perch-nielseniae - more rectangular shape than obliqua NP23-NN6 
H. orientalis - small, quadrate, with tow large openings NN6-11
