I attached a close up photo of the top. I thought it was tapered because the mouth of the top is narrower than the base of the top which is unevenly applied, like a drip edge.
The concentric rings go completely around the bottle. Very faint so difficult to see in the image, but i can feel the rings as I slide my finger along the side of the bottle. First ring is 4 cm from the base, second ring is 3 cm above the first, and the third ring is 2.5 cm above the second...
I recently found this glass bottle buried in the mud at low tide on a remote beach in the Gulf of California near La Paz, Mexico. Bottle is 26 cm height and 6.5 cm diameter at base. Color light bluish green and very frosted and scratched from long time in marine environment. Applied blob top...