To the east of the lagunes, and north from the city of Este, we find the _Euganian_ mountains, or hills, forming, in the midst of a vast alluvial plain, a remarkable isolated group of rounded hills, near which spot the fable of the ancients supposes the fall of Phæton to have taken place. Some writers have supposed that this fable may have originated from the fall of some vast masses of inflamed matters near the mouths of the Eridanus, that had been thrown up by a volcanic explosion; and it is certain that abundance of volcanic products are found in the neighbourhood of Padua and Verona. The most ancient notices that I have been able to procure respecting the situation of the shores of the Adriatic at the mouths of the Po, only begin to be precise in the twelfth century. At that epoch the whole waters of this river flowed to the south of Ferrara, in the _Po de Volano_ and the _Po di Primaro_, branches which inclosed the space occupied by the _lagune_ of Commachio. The two branches which were next formed by an irruption of the waters of the Po to the north of Ferraro, were named the river of _Corbola_, _Longola_, or _Mazzorno_, and the river _Toi_. The former, and more northern of these, received the _Tartaro_, or _canal bianco_, near the sea, and the latter was joined at Ariano by another branch derived from the Po, called the _Goro river_. The sea-coast was evidently directed from south to north, at the distance of ten or eleven thousand _metres_[388] from the meridian of Adria; and _Loreo_, to the north of _Mesola_, was only about 2000 _metres_[389] from the coast.