Interesting to read about the martlets in the Delta Chi magazine. My family is linked to the Leftwiches of England. In describing our Coat of Arms,
Martlets (mythical footless swallows who loved flight so much they never landed, therefore they didn’t need legs) are thought to represent the swift. Since the swift never lands this symbol has been used as a sign of a younger son who has no land of his own, therefore no place to rest. It may signify one who has to subsist by virtue and merit, not inheritance. It is also thought that this is an emblem of one who has been on a pilgrimage to the Holy Land.
Stefan Oliver, An Introduction to Heraldry, Quantum Books, pp. 70.
http://leftwich.org/ArmsMeaning.htm