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Revision of H. recta group from Sat, 15/03/2008 - 19:50

Sat, 09/08/2008 - 23:55 — Anonymous
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 
 recta_Theod84.jpg H. recta - large pores separated by horizontal bar   NP24-NN1
 obliqua_Theod84.jpg

H. obliqua  - trar-drop shaped with narrow, distinctly oblique,

openings

 NP24-NN6
 perch-nielseniae_Theod84.jpg H. perch-nielseniae - more rectangular shape than obliqua  NP23-NN6
orientalis_Theod84.jpg  H. orientalis - small, quadrate, with tow large openings NN6-11 

 

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