This stitch is used to fill a small shape with an open pattern. When the stitches for the shape are open (not right next to each other), then they will not overlap properly as they do with the Fishbone Stitch. To make them overlap, turn the center guideline into two lines.

The stitching sequence is a little different from the Fishbone Stitch. Half of the stitches are worked from a center line to the outer edge, and half are worked from the outer edge to the other center line, as shown in this drawing: