Y. Israeli, Made by Ennion: Ancient Glass Treasures from the Shlomo Moussaieff Collection, exhibition cat. (Israel Museum), Jerusalem, 2011, p. 76.
For examples of this type of beaker see Stern, 1995, pp. 103-108, no. 8 and Whitehouse, 2001, pp. 13-14 and pp. 27-29, nos 492-496. There are various types of these beakers with different complexities of mould. This type, with stepped knobs, bosses and masks is the most complex and rare. For a similar beaker in the Archaeological Museum, Split (no. G1551) see Rnjak, 1979, p. 236, no. 476. Fragments from the lower part of a beaker seemingly blown into the same mould with four masks were found in the Necropolis of Zara; see Ravagnan, 1994, p. 124, no. 233. Various interpretations of the knobs have been offered including lotus buds, almonds, knots in a tree trunk and the knots on the club of Herakles. They have been found all over the Roman empire from St Albans to Israel.