Tappit hen : A hen having a tuft of feathers on her head.

Tappit hen : A measuring pot holding one quart (according to some, three quarts); -- so called from a knob on the lid, thought to resemble a crested hen.

Example:


Taxonomy
Fact Monster, pewter, pot, quarts, claret, Dictionary of Phrase and Fable, Reference Desk, English, Waverley, chap, the Baron, Bordeaux, belt, chickens, drinking mugs, tap, Jeroboam, Weel.

Defination from the web:
Tappit-hen (A). A huge pewter measuring-pot, containing at least three English quarts. Readers of Waverley will remember (in chap. xi. ... A hen and chickens means large and small drinking mugs or pewter pots. A tappit was served from the tap. ( See Jeroboam. ...