This ancient Roman measure (lat. shell or bowl) was, along with the sextarius, one of the most widespread standard measures in ancient Rome. Liquids were originally calculated by weight. The largest known measure of volume was the 160 congii (= leather bag, tube) with 524 litres, i.e. about two barriques. The amphora (26.25 l) was used as the trade measure, it was divided into two urna (about 13 l).
The sixth part of a congius was called a sextarius, which corresponded to 0.54 litres and was, according to today's terminology, a pint or jug. The third part was called Triens with 0.18 litres, the fourth part Quadrans with 0.135 litres, the sixth part Sextans with 90 cm³ and the twelfth part Cyathus (scoop) mentioned in the novel Satyricon with 45 cm³. The list connects the most important hollow measures to each other (but there were much more). The dimensions are not necessarily compatible with each other and should only be taken as guidelines. See also the keywords barrel types, bottles, hollow measures and wine vessels.