The earliest known seal of the University perhaps dated from around 1261: the earliest surviving impression is on a 1291 deed in Peterhouse. It showed the Chancellor, seated and holding a book, between two figures apparently engaged on a disputation. Under them is an arched bridge of four lights over a river, certainly the Cam, accommodating three fish.This seal was replaced, probably early in the 15th century by another seal of similar design, with the seated and standing figures each in a canopied niche and under them a flat bridge of only three lights, and a river boasting only two fish. For a fuller account of these seals, and of the official seals of the Chancellor, as well as of many college seals, see W. H. St John Hope in Proceedings of the Society of Antiquaries, 25 Feb. 1885, pp. 225-52.