There are a few words we still need to learn to use properly. These words are what cause arguments among grammarians and writers.
For example, is it correct to say, “The forest contains myriad species” or “The forest contains a myriad of species.” The argument is usually that myraid is an adjective equivalent to a number and since you cannot say “there are a ten thousand of species,” you shouldn’t say, “There are a myriad of species.”
Would you be surprised if we told you that most language experts believe both ways are fine?
Myriad was actually used as a noun in English long before it was used as an adjective, and today it’s considered both a noun and an adjective, which means it can be used with an ‘a’ before it (as a noun) or without an ‘a’ before it (as an adjective).