Setting font to Lucida Grande on Mac OS X

[Sancho Neves-Graca]

I am running Emacs 21.3.50 Carbon Mac OS X 10.2.6.

I would like to change the font of a frame from the default (Monaco) to 
the system default (Lucida Grande). The following fonts can be set:

M-x set-frame-font RET -*-Monaco-*-120-*
M-x set-frame-font RET -*-Courier-*-120-*
M-x set-frame-font RET -*-Helvetica-*-120-*

But putting in ~/.emacs

(set-default-font "-*-Lucida Grande-*-120-*")

returns Font '-*-Lucida Grande-*-120-*' is not defined.

Is Lucida Grande available for Emacs on Mac OS X? If so, what is its 
identifier?