On the largest stone of those discovered in 1711 under the choir of Notre-Dame was deciphered an inscription which recorded the erection of this altar to Jupiter, "very great, very beneficent," in the reign of Tiberius Cæsar, by the corporation of _nautæ_, or mariners, apparently the most powerful in the city, and the prows of the ships at the foot of the arches in the ancient palace of Thermes are supposed to have been connected with the same guild, though this architectural ornament is by no means uncommon in ancient art. It is from these _Nautæ Parisiaci_ that the modern city derives its arms,--a vessel with distended sails. (If any doubting tourist inquire concerning the maritime commerce of Paris, he will be proudly referred to the barges which may be seen at all the quais, and, even more, to the little steamers from London which contrive to get under the bridges.) In some of the modern records this ancient corporation is given great importance--with many _sans doutes_ and _il paraîts_--in the history of the city, both before and during the sway of the Romans. Cæsar found it "fully organized," though it was founded on the Roman corporation of the _Nautæ Tyberis_, navigators of the Tiber, composed of senators, magistrates, and knights, which transported grain and other merchandise from the port of Ostia to the capital; and it was the original of the later _maison de la marchandise de l'eau, de l'hôtel de Ville et du conseil municipal_ of Paris. The activity of the Lutetian shippers and navigators covered the territory bathed by the Seine, the Marne, and the Oise, all of them quite navigable. The ruins of the Gallo-Roman buildings discovered in the Cité in 1844, at the opening of the Rue de Constantine, were the remains of a market or forum for the sale of provisions; and the corporation had, near the port, an office or bureau for the regulation of this river commerce. Opposite the port, on the northern side of the Seine, they controlled also another point of landing, at the Grève, where, later, was established the _prévôté de l'eau_, which developed into the Parisian municipality. The port on the Cité, on the larger arm of the Seine, received in the Middle Ages the name of Saint Landri, this bishop having had an oratory, and perhaps his residence, in the neighborhood. Under the Later Empire, in the reign of Posthumus, the northern suburb having increased in size and importance, a market was placed at the Champeaux, on the site of the present Halles Centrales, and the port of the Grève became, as it has remained ever since, a point of landing for merchandise coming from the upper Seine. The port on the southern side of the river, near the great road from Genabum, was established on the site of the mediæval _Quai de la Tournelle_, the great tower which replaced that of the southern wall of fortification of the city built by Philippe-Auguste. This quai still serves at the present day as a landing-place for the barges.