In the case of Aeschylus and Sophocles the numbering of lines agrees with that in the translations of Plumptre and in the original. In the plays from Euripides the numbering is that of the lines in the cheap translation (Routledge's Universal Library).
[Transcriber's note: In the original book, the line numbers mentioned above were right-justified. In this e-book, they are enclosed in curly braces, and placed immediately after their associated line of text, e.g. ". . . a line of text {123}".]