There's really no such thing as one "perfect" face, but in 1934, actress Sylvia Sidney's was considered ideal.
Sidney's face was chosen as a standard of beauty because of its symmetry and oval shape by a conference of Southern California cosmetologists, all of whom worked in film makeup. "The elliptical symmetry of Miss Sidney's features made our choice an easy one," Paramount makeup artist Wally Westmore told The Day in a July 1934 article.
The below image shows Sidney's face annotated as a guide for studio makeup artists. Some her "ideal" features include the fact that the length of her face equals the length of three noses and that her upper and lower lips are the same width.