They are internal thread bottle stoppers. The internal thread bottle and stopper was in vented in the US before the Civil War but never caught on. The patent expired and English glass houses started using it some time in the 1870s. The stoppers were made from wood, a hard rubberized type of plastic and rubber coated wood.
I must agree with Capsoda on this one they are internal thread bottle stoppers or as we say in Ca. inside screws. I have a few Ca. whiskeys with this type of top...What it says on the stoppers might also be a clue.. But Capsoda pegged this one..I think..[]
Thanks for the heads up... I wasn't a member of this wonderful forum when that was posted but it is a great example of an internal thread and a Beautiful bottle...thanks again.. Norene