Couple.

[Laurence Horn]

At 9:55 AM -0500 12/7/00, Thomas Paikeday wrote:
>Why not "a dozen of eggs"? I think the same rule as in "12 of eggs"
>applies here. But I leave it to professional linguists to give a
>linguistic explanation.
>
I think these are different, at least historically.  "a dozen" and "a
couple" were originally nominals taking complements, and the former
still is in its source language, French, while numbers were never
primarily nominals/substantives (leaving aside the 4 of spades,
etc.).  The fact that "a couple of Xs", not to mention "a lot of Xs"
(where again "lotta" is standard colloquial), always determines
plural agreement indicates that it's no longer the head of the NP but
a sorta predeterminer, but it did start out as [dozen [of eggs]],
like [couple [of horses]].  The OED makes it clear that the earlier
uses of the former did indeed have this form--while also revealing a
much more understanding attitude toward the cardinality of "dozen"
than it does toward "couple":

'Originally as a sb., followed by "of", but often with ellipsis of
"of", and thus, in singular = twelve. Also, used colloq. in pl.,
either indefinitely or hyperbolically, for any moderately large
number'.

Larry