Tabula (plur. tabulae): Transverse porous partition linking both walls of a two-walled cup.
NB: subdivided pores and concentrical pores are often similar on tabulae. Examine walls to discriminate them or choose both states.
Simple: Circular perforation.
Slitlike: Elongate elliptical shaped.
Pecten: Thin-tooth comb (with rods) structure.
Divided pore: Pores irregularly divided by radial protrusions of lintels.
Concentrical pores: Pores are grouped into more or less discrete clusters.
Irregular: No geometrical pattern.
Microporous membrane: Thin horizontal structure irregularly porous.
Presence of tabulae | |_ Pores shape of tabulae