Martlet

A heraldic bird, shaped like a martin or swallow and always depicted without legs, with short tufts of feathers in their stead divided in two parts, somewhat like an erasure, and forming, as it were, thighs. The martlet is not only a very common bearing in heraldry but, as a mark of cadency, it is the peculiar difference of the fourth son, thereby implying, that as these birds have no legs to alight upon, so younger sons, having little land to settle upon, must trust to the wings of virtue, merit, and industry to raise and support themselves. See also Merlette or Merlion