Seif

Such seifs have a somewhat zig-zag form instead of a fairly straight line. On the top of seifs small transverse dunelets are very often found, and these may be likened to almost straightened-out barchans.[…]On the top of the seif they form a wave-like pattern with a fairly defined "wavelength".

Though the actual transition forms suggested in Fig. 76 do exist and have been examined by the author, the above tentative explanation of the growth of a seif dune chain should certainly not be taken as implying that all such chains have originated as barchans.

Seifs are longitudinal forms elongated parallel to the prevailing wind direction.

Tsoar, H. Dynamic processes acting on a longitudinal (seif) sand dune .