By linear, or perhaps, more correctly, rectilinear incision.
The English letters are much more sober and rectilinear in character.
Patagium incomplete, enveloping only the basal half of the arms, with four to five rectilinear parallel chamber-rows.
Kepler, on the other hand, was no less in error in considering their paths to be rectilinear.
Quite soon you will begin to find ...