Dance in cotton is Hollywoodโs fashion slogan straight through the summer. Margaret Lockwood, now in Paramountโs Rulers of the Seas, wears this beguiling, slim dance dress of white cross-bar muslin with a high waistline and narrow shoulder straps. If the mood permits, Miss Lockwood may wear a brief bolero of bright cerise quilted taffeta, which serves smartly as a youthful wrap.