Myriad / myriad of

Both should be correct. One is used as a noun, the other used as an adjective. But what I'm not sure about is if there are any differences in nuance. For instance, saying "many apples" and "many of the apples" are quite different in meaning; the former means a lot of apples and the latter is a subset of a larger pool of apples.

dyske is correct: "Myriad" is both a noun (with a much older history) and an adjective. Originally, "myriad" meant ten thousand; its second meaning is "a great many," hence "a myriad of [something]."

As an adjective it means "innumerable": John had myriad reasons for not finishing his homework, all of them plausible.

A 10,000 of apples? A 10,000 OF APPLES???????? That's broken english!

"A 10,000 of apples" is indeed poor English; however, as was pointed out, the original meaning of "myriad" was 10,000. That's no longer the common meaning. Thus, "a myriad apples" and "a myriad of apples" are both correct. Normally, though, when we're counting apples, we use pounds, kilograms, bushels, or simply, "a lot" to describe a large number.

@Steve_Hall: I don't care. A myriad apples seems more correct to me. Note that a many of apples is also Engrish (broken English).

While I begrudgingly admit both might be correct, I'll continue using it as an adjective. It's all I have left to maintain any modicum of superiority over other authors.