Note 3257 — Chapter XXI · ROMAN POTTERY: TECHNICAL PROCESSES, SHAPES, AND USES
Reading edition
Florida, ii. 9, 2: cf. the terracotta vessels with reliefs in the British Museum, D 204-5; also Mus. Greg. i. pl. 10; Micali, Mon. Ined. pl. 52. Isidorus derives the word from ampla bulla, in reference to its rotund form (Etym. xx. 5).