what's the dog's name?

I know the Nurse is a semi-literate babbling woman, but what on earth is going on about here? Why is she talking about the letter R? Where did Rosemary come from? Can someone throw a little patch of light on this?

Nur. Well sir, my Mistresse is the sweetest Lady, Lord,
Lord, when 'twas a little prating thing. O there is a Noble
man in Towne one Paris, that would faine lay knife aboard:
but she good soule had as leeue see a Toade, a very
Toade as see him: I anger her sometimes, and tell her that
Paris is the properer man, but Ile warrant you, when I say
so, shee lookes as pale as any clout in the versall world.
Doth not Rosemarie and Romeo begin both with a letter? **
Rom. I Nurse, what of that? Both with an R
Nur. A mocker that's the dogs name. R. is for the no,
I know it begins with some other letter, and she hath the
prettiest sententious of it, of you and Rosemary, that it
would do you good to heare it
Rom. Commend me to thy Lady

thanks to anyone who has a clue.

Eight lines of dialogue into of R and J has Sampson saying:

"A dog of the house of Mountague, moues me."

Considering the later business with the dog's name, it seems to me reasonable to suppose the dog to whom Sampson refers is Romeo.

Any thoughts on these matters would be gratefully recieved by the way.

There's no need to be shy.

The nurse can't read so she asks about R.
Rosemarie comes from rhyming, it's for remembrance.
Any old dog I think.