http://augustuscoins.com/ed/Christian/ChristianSymbols.html There is one type mentioned in older literature that I doubt exists. On my site it says, "This is a line drawing copied from an article on early Christian symbols on coins. It is not certain that there really is a coin like this with a clear rho. If you have evidence it exists, please contact me. [It gives my e-mail.] Do not misunderstand what I am asking by exhibiting coins like this: Constantine II Struck 319-320 at Ticinum 19-18 mm. 2.05 grams. 5:30. RIC Ticinum 121, page 377 Note the bump at the top of the Iota. It is not a rho, but it is close enough to induce scholars from long ago to write that this type exists with a chi-rho. I think it is a different symbol, like this: That is an example taken from page 234 of the massive book, Imperator Caesar Flavius Konstantin Constantinus der Grosse, Ausstellungskatalog herausgegeben von Alexander Demandt und Josef Engemann. What I am asking is if anyone has a coin, or an image to show us, where it is undoubtably a chi-rho with a clear rho and not just a line with a bump?