"...is elongated in the direction of one of the edges of the octahedron..." -The Encyclopedia Britannica…
"...is flattened parallel to one pair of faces [of the octahedron]." -The Encyclopedia Britannica 1910
The illustration "shows how the octahedron with furrowed edge may be constructed from two interpenetrating…
An illustration showing "two octahedra...united by contact along a surface parallel to an octahedron…