From Strunk and White's The Elements of Style, Chapter 2, Lesson 2:
In a series of three or more terms with a single conjunction, use a comma after each term except the last
Thus write,
- red, white, and blue
- honest, energetic, but headstrong
- He opened the letter, read it and made a note of its contents.
My question is: Why isn't there a comma after read it in the third example?