E.g.
is short for exempli gratia, and is in common use to introduce an example within a sentence.
Submit a sample of academic writing, e.g., a dissertation chapter.
However, some authors use ex.
or ex:
(short for "example") for the same purpose, and this form is listed in some authorities like the Wiktionary.
Submit a sample of academic writing, ex: a dissertation chapter.
I know they both roughly mean "example", but which one should I use, and when? Are there connotations associated with one or the other?
This question has been asked elsewhere, and this very answer comes up when you ask Google about the difference. It would be good to get an EL&U answer for it.