Bract: Plate stems from lintels which incompletely covering a single pore.
Lintel: Skeletal structure separating and bounding adjacent pores.
Carcass: Part of wall on intervallum side.
IW: Inner wall.
Canal: Pore modified by skeletal structure thikening or by lintels streching. Canal length is greater than perforation diameter.
Lintel: Skeletal structure separating and bounding adjacent pores.
Inner wall: Internal part of the skeleton, separating central cavity and skeletal structures, composed by a porous carcass, simple or coated by an additional sheath.