Most other examples of this type have rounded bodies that taper downward (e.g. Isings’ line-drawing ), so this piece could be a slightly later development or a regional variation. The closest parallels (all of which have rounded bodies) are Simonett, fig. 62, no. 16a, Hayes, nos. 102 and 103, Fleming (1996), fig. 18 (which is mold blown), and Whitehouse (2001), no. 770. - Ancient Glass in the University of Colorado Museum