Printers Marks (ModE "colophon" when at the foot of a title page near the publisher's name)

Aldus Manutius, Venice, 1450-1515 (and used after his death by his heirs)

Aldus' device, the dolphin and anchor

William Caxton, Westminster, ca. 1422-1491 (and used after his death by Wynkyn de Word, his former pressman and possibly his heir)

Printer’s mark of Caxton