Antonio Sciarretta's Toponymy
Common remarks: the place-names are given in the nominative case
A second stratum, maybe older is the one that I propose to call Liguro-Sicanian. This hypothetical language can be traced from a number of placenames, mainly of mountains and rivers like the very Alpes m. and Padus fl., showing a peculiar consonant shift, e.g., *bh>p, *dh>t, etc. Such a stratum could have occupied the whole Tyrrhenian coast of Italy before the Western Italic branch.
A third group of placenames is of difficult attribution. Some of them show an initial p-, which excludes a Gaulish origin, but at the same time they do not show the typical Ligurian consonant shift. Actually this Pre-Celtic stratum, if a separate language group, seem to have had a very regular consonant system, so maybe it is rather old. The situation is similar to that of the Lusitanian language in Iberian peninsula, or of the generic Alteuropaeisch stratum postulated by many scholars.