posted by Schuyler .
What is the role of the Choragos, or chorus leader? Why are there times when only the Choragos speaks, and not the entire chorus?
Scroll down to Characteristics of the building and read about the choragos toward the end of the first paragraph of that section.
Also this: http://www.answers.com/choragos
You already have some excellent sites and here are a few as well:
Antigone is a wonderful example of the use of this.