The earlier 18th C. beads, probably made at Venice and Holland, are distinctive—and you have shown some. In this image, the central bead of the middle (2nd) strand may be one. Most of the rest of these beads appear to be the 19th-20th C versions made at Venice.

I call these "meander" beads. Others call them "snake" beads—which I find problematic, since there are already "snake" beads from Czechoslovakia.

Jamey