Antonio Sciarretta's Toponymy
Common remarks: the place-names are given in the nominative case
Not considering obvious late Latin names, there are traces of two more strata. The former, probably the oldest, can be reconducted to the wide family that I propose to call Liguro-Sicanian. These names can be recognized for the typical shift of the type *bh>p.
A third stratum could include names that are not Ligurian, since they don't show the typical Ligurian consonant shift, but cannot be Celtic either, since they show an initial p or they derive from appellatives which are different in Gaulish. This tentative stratum is called here Pre-Celtic.