Fig. 7 in A new genus of Norian involutinid foraminifers: Its morphological, biostratigraphic, and evolutionary significance

Fig. 7. Tubular chamber section concept in Involutinidae. Aulotortus: tubular chamber simple, without internal structures; Aulosina gen. nov.: tubular chamber lumen constricted by strenghtenings; Triasina: tubular chamber supported by inner−pillars. Note similarities between sections of different genera. The axial horizontal section of the tubular chamber is the most reliable for a generic identification.