Lace-Up Back Long Prom Dress: Atria 6520HStand out with confidence wearing this long mermaid prom dress 6520H from Atria Couture. A curve hugging design from the scoop neckline to the horsehair hem, this elegant long evening gown has thin shoulder straps that attach to thin bands that lace up over the open back. Offered in misses and some plus sizes, this glamorous long formal dress hugs the hips before draping to the floor and pooling into a small train that trails behind every step.