This article is the first complete documentation and analysis of the ancient sources for the Saturnian metre. There are three main questions: (i) What can we say about the development of the name 'numerus Saturnius' resp. 'numerus Faunius'? What did it mean? (ii) Which characteristics had been attributed to this metre? (iii) What did the ancient authors know (or think) about its nature? (And what do they offer more than mere description of evident details?) The relevant passages are presented, usually with Latin text and a German translation, and broadly discussed in this article. The discussion of the text is focusing on all issues of metrical data that can be gained from the text, and the dependencies of tradition and the innovations of the authors are recognized. Finally, the questions raised at the beginning are answered (as far as possible).