martlet

A representation of a bird without feet, used as a crest or bearing to indicate a fourth son.

The martin, a bird.

In heraldry, a bird represented with the wings closed and without feet, but often retaining the tufts of feathers which cover the thighs.

The European house martin.

A bird without beak or feet; — generally assumed to represent a martin. As a mark of cadency it denotes the fourth son.

A mythical bird, often used in heraldry, which possessed no feet.