What is Bastardus Non Potest Habere Haeredem Nisi De Corpore Suo Legitime Procreatum?

Legal Definition
A bastard can have no heir unless it be one lawfully begotten of his own body. Tray Lat Max. 51.
Legal Definition
A bastard cannot have an heir unless one lawfully begotten of his own body.
-- Ballentine's Law Dictionary