the 1st illustration shows digital reissue of english monotype ornament 280. john ryder called this unit «A Venetian Arabesque» [A Suite of Fleurons, charles t. branford, boston, 1957, p21], as he believed its exemplar first shown by the venetian printer gabrielle giolito in 1552 (2nd illustration). i had a eureka moment spotting the giolito ornament used on the title-page of the 1553 Il Petrarca printed by contemporary venitian printer domenico giglio (3rd illustration). however, hendrik d.l. vervliet confirmed that this arabesque was engraved by robert granjon, & first shown in the paris printing office of denis janot in 1544 [Granjon’s Flowers, oak knoll press, new castle (del), 2016, p23]; vervliet’s ornament is the same as used on the giglio title-page. on closer comparison, the monotype 280 is not an exact copy of the granjon unit, but an abstraction made more symmetrical (4th illustration): perhaps its exact exemplar is to be located on a specimen page from a later foundry [✓].
with thanks to the john rylands library for permitting my examination of the giglio petrarca.