Cors y Gedol

Coeten Arthur – Literally, Arthur's Quoit – a cromlech near Llanddwywau, having the print of a large hand ingeniously cut on it, as if sunk in from the weight occasioned by holding it. It is a large flat stone somewhat of an oval form, about ten feet long, and, in the widest part, nearly seven broad, two feet thick at one end and not more than an inch at the other. It stands upon three rude stone pillars, each about half-a-yard broad. – Ed. Tr.

p152 in 'Transactions of the Cymmrodorion' v1 (1822). The first part of this seems to be copied from 'The Cambrian Register for the year 1795', except that says 'a large hand dexterously carved on the side of it'.