Cunniform

Cuneiform: wedge-shaped (∆ ALP Delta). Letters used in ancient Sumerian, Akkadian, Assyrian, Babylonian, and Persian writing.

Cunny: slang for 'vagina' and related to the word 'cunt'.

"with a meusic before her all cunniform letters" describes this chapter (if not the whole of Finnegans Wake).

Joyce asserted that parts of the Wake were "pure music" and "pleasing to the ear".

'Anna Livia Plurabelle' begins with the delta-shaped, cunny-form triangle, topped by an opening suggested by the letter "O". The chapter's structure is therefore "cunniform".

That all the letters are cuneiform, and therefore wedge-shaped, suggests that her name and symbol are written everywhere (particularly in the form of the thousand-or-so river names running through the text).