AHHHHHH,it looks like a infinity symbol,...lol....
Y G And Co,......its not in this book,"400 trademarks on glass",grab on amazon etc etc..
But it is a great bottle,... I only have a few poisons--strange
It appears to be a Victorian poison, probably English or at least Brittish. I havent found the mark yet , my sources for European marks are somewhat limited.
Most definitely a UK poison bottle from the 1900 - 1920 pieriod,,
Believe that Y G & Co stands fro the york glass works company but may need a little further research on that one
These poisons are readily available in the UK