Polygonia comma form of comma is frequently confused with the dark form of the question mark ("P. interrogationis"), but the two can readily be distinguished by the shape of the comma mark on the underside. The pale form is easily confused with the satyr comma ("P. satyrus"), which usually occurs north and west of the eastern comma's range. They can be distinguished by the upperside color, which is orange brown in the comma and tawny yellowish brown in "P. satyrus"; by the underside pattern, which tends to be mottled in the comma but appears to be more longitudinally streaked in "P. satyrus";
That is often omitted when used to introduce a subordinate clause—""He told me that it is a good read."" could just as easily be ""He told me it is a good read."" Historically, "that" usually followed a comma: "He told me, that it is a good read." Middle Modern English grammarian Joseph Robertson recommended in "On Punctuation" that a comma be used with a conjunction. However, if the subordinate, conjunctional ellipse, null complement, or syntactic pleonasm of "that" is punctuated with a comma, then, in the English grammar, stylistically speaking, it is a comma splice, especially in formal writing. Instead, a