Antonio Sciarretta's Toponymy
Common remarks: the place-names are given in the nominative case
A more speculative stratum is that of the "Pelasgians". According to my personal reconstruction, these pre-Greek language characterized by a typical consonant shift (e.g., *d>t) is responsible of some placenames. The Pelasgians should be identified with the "Tessali" mentioned by some classical source (e.g. Strabo) and they may be arrived at the seabords of Northern Adriatic, as well as in other parts of Italy, particularly Southern Etruria.
A minor number of placenames could have been related to Etruscan (non-IE) language. At least one place name is likely Umbrian. Many others could have been originated from a Pre-Celtic language, also differing from Ligurian (at least in the sense here given to the name "Ligurian")