A wonderful original sewing dress pattern McCall #3666, size 18.  The pattern is dated 1921 and features two different dress styles. It is a Printo Gravure with cutting and assembly diagrams printed on the pieces.  Some of the 6 pattern pieces are uncut. 

Shape of the dress is a long bodice with gathered skirt sides and back. Straight skirt panel at center front.  One style is sleeveless with round neck line.  Other style features cap sleeves and V collar. 

According to the diagrams, the dresses could be embroidered, although I did not find any stencils, and couldn't find any information to suggest there were stencils included. 

Size 18.  Bust 36", hip 39" ,

Condition of pattern.  For the age, I would say, very nice.  As mentioned, some pieces have been cut and others not.  However, all pieces in nice condition. Envelope has its few wrinkles and small tears but it, too, is quite presentable.