116	NATURAL HISTORY OF GEMS.
	for their most important works. Their intagli were not, like those of the ancients, confined to the small dimensions of signet-stones, but were designed to be worn as medallions, to be set in plate, or to form the panels of reliquaries or caskets (being laid upon a coloured ground), for all which uses extent of surface and transparency were the greatest recommendations. The fame of Valerio, il Vicentino, chiefly rests upon his large plaques of Crystal engraved with elaborate compositions done in his own peculiar and forcible stylo, of which numerous specimens (due to his incredible industry through the course of a long life), are everywhere to be seen in collections. The most important of these was the coffer adorned with the History of the Passion, a commission from Clement VII. at the price of 2000 gold scudi, designed for a present to François I., on their interview at Marseilles, where they arranged the marriage of the Dauphin with Catarina dei Medici. Vasari especially commends the Crystals of Valerio's rival, Grio. del Castel Bolognese, particularizing as his best the Tityus, after the design of M. Angelo, and the Ganymede engraved for the Card. Ippolito dei Medici. Another famous work of his was the Attack on the Castle of Bastia, done for Duke Alfonso of Ferrara. A Lion-hunt by this artist, now in the Devonshire Collection, fully justifies the encomium of Vasari. These plaques are usually of considerable size, one of Valerio's in the Uzielli Collection measuring 3-1/4 x 2-1/8 inches. Mariette says that the Tityus and the Fall of Phaethon were executed after drawings furnished by M. Angelo, and suspects that Perin del Vago supplied those for his scenes from the Life of Christ adorning the bases of the Cross, and two candlesticks presented to St. Peter's altar by the Card. Alessandro Farnese, the engraver's latest and chief patron. Smaller intagli of this date in Crystal are sometimes