Zigzag Chain Stitch

Worked in the same way as Chain Stitch, but along two parallel lines to form a zigzag pattern. To keep the angled loops lying flat, when reinserting the needle through the fabric, stitch through the end of the last loop.

Elegant Stitches, p 63
Mary Thomas's Dictionary of Embroidery Stitches, p 42 [Vandyke Chain Stitch, Zigzag Chain Stitch*]