This character wears Pantalettes.
Pantalettes are undergarments covering the legs worn by women, girls, and very young boys (before they were breeched) in the early- to mid-19th century.
Pantalettes originated in France in the early 19th century, and quickly spread to Britain and America. Pantalettes were a form of leggings or long drawers. They could be one-piece or two separate garments, one for each leg, attached at the waist with buttons or laces. The crotch was left open for hygiene reasons. They were most often of white linen fabric and could be decorated with tucks, lace, cutwork or broderie anglaise.