A sculptor named Bonaiuto must, I think, have belonged to Niccolò's school. Two interesting sculptured doorways by him still exist in what was once the Palazzo Sclafani at Palermo (now the barracks of S. Trinità). The doorway is carved in _tufo_, and above it is a kind of gable supported by two small pilasters, enclosing the arms of the family, a pair of cranes; surmounting the gable is a carved eagle, with a hare in its claws, standing on a kind of capital, which is unmistakably Comacine; beneath this is a bracket inscribed, "_Bonaiuto me fe-cit de Pisa_." Sig. Centofanti, in a private letter to Professor Clemente Lupi, who wrote to ask for information about Bonaiuto, says that a register of expenses of the Opera del Duomo of Pisa contains several mentions of the name. In one dated 1315 _Bonaiutus magister lapidum_ is noted as working at the Duomo, and receiving two soldi a day, his companions receiving four or five, and the _capo maestro_ eight. Here it would seem he is still in the lower ranks of the brotherhood. In 1318 he is noted as Boniautus Michaelis, and receives four soldi a day. In 1344 he has become full _capo maestro_ of the Duomo, and is paid nine soldi a day.[174] From his school also sprang Arnolfo, the first of a long line of sculptor-builders of the Florentine Lodge. From it, too, through his son Giovanni, came the best builders of the Siena cathedral, and their followers who worked at Orvieto. Thus Niccolò and Giovanni are proved to be links in the old chain that came from classic Rome through the Lombard Comacines to the Renaissance. All the famous names that ever were, may be traced in this universal Guild from father to son, from master to pupil. After Giovanni Pisano went to Siena, Andrea di Pisa, his scholar, carried on his school in Pisa. In 1299 we first hear of Andrea, the son of a notary at Pontedera, as _famulus magistri Johannes_.[175] His first authentic works were the bronze doors of the Florentine Baptistery, proving that he had been trained in the many-branched fraternity at Pisa, where metal-working ranked so high. As instances of his sculptures in marble, we may take many of the statues which were on the Duomo at Florence, and the second line of reliefs on Giotto's campanile. But like all the _Magistri_, he was, above all, an architect, and in that branch we find him as Grand Master at Orvieto in 1347. His son Nino succeeded him in the onerous office. His other son Tommaso was also in the guild, but did not rise to eminence in it. He designed a palace, and painted two caskets for the Doge dell' Agnello of Pisa. Nino's sculptures show a greater fidelity to nature than those of his artistic ancestors. A Madonna and two angels over the door of the canonry of the Duomo at Florence are very charming, as are his statues in the church of the "Spina" at Pisa. We next find Nino's son Andrea receiving payment for a sepulchre for the Doge dell' Agnello, which Nino did not live long enough to finish.