Antique flint glass lid, c1830 - 1870. I believe it was made by Boston & Sandwich. I'm not sure if it belongs with a pharmaceutical, poison or toilet water bottle, as it is quite small. It is not a stopper, it would slide over the top of a rimless bottle.

Measures 2" tall & the inside diameter of the rim is 3/4" .

Excellent condition with 1 micro nibble on the top finial's edge (see below), & 1 flake on the bottom rim (see below).