Gastromancy

1693 Urquhart translating Rabelais Gargantua & Pantagruel iii. xxv. By Gastromancy, which kind of ventral Fatiloquency was for a long time together used in Ferrara by Lady Giacoma Rodogina, the Eugastrimythian Prophetess.

1610 Vives in J. Healey Saint Augustine of the Citie of God Diuination generally was done by diuers means..Hydromancy..done either in a glasse bottle full of water, wherein a Childe must looke, (and this is called, Gastromancy of the glasses belly)...

The methods [of scrying] varied according to the nature of the shiny object used and the medium employed... Sometimes the term gastromancy ('divination by the belly') was used, because the vessel filled with water was called gastra 'belly-shaped vessel'.