Any beast can be cut in half to become a demi-beast, and used as a charge. The treatment is found in period armory: demi-lions are found in the arms of Hamme, c.1312 [ANA2 243]. While demi-beasts may, of course, be issuant – e.g., from base, from a fess, or from a line of division – they are frequently found as discrete charges.
A demi-beast is erect by default, even when this is not the default posture of the full beast. The severed part is couped by default; if the demi-beast is erased, the fact must be blazoned. The couping is roughly fesswise, and frequently includes a snippet of the tail as well. The illustration shows a demi-lion.
Katherine Brianna Coldrake Kyven bears: Argent, three demi-horses rampant to sinister purpure.
Rhianwen ni Dhiarmada bears: Sable, a demi-unicorn rampant Or crined and horned argent.
Brian mac Tomáis Uí Fhoghladha bears: Argent, a demi-goat erased gules.
Ivan Geirsson bears: Sable, three demi-lions Or.