The pithon is a reptilian monster, essentially a bat-winged serpent. It is sometimes called an “amphiptère”, especially in French blazon. When leaping, it may also be called a “jaculus”; if the wings are feathered (bird’s) wings, rather than bat-wings, it should be blazoned a “winged serpent”. No heraldic difference is granted between the two forms.
The pithon is a period charge, found in the arms of the Portuguese poet Camões (d.1580) [Woodward 294]. Brooke-Little has shown [Her.Alph 170] that the heraldic pithon is a variant of the wyvern, and in some cases was drawn as such; thus no difference is granted in the Society between the two monsters.
Society heraldry doesn’t seem to define a default posture for the pithon; “erect” is the most common, in which posture the wings are addorsed, as in the illustration.
Llywela o Landaff bears: Or, a pithon erect purpure.
Reynald il Bianco bears: Per chevron inverted sable and gules, overall a winged serpent erect displayed argent.
Ilya Azhtelstinevich Gryaznie bears: Per bend sinister vert and argent, a jaculus, his wings above the line of division, counterchanged.