The rivers were perhaps Arno, Tiber, Metauro, Po, Taro, and Ticino.

This we gather from a letter written to Michelangelo on the 23rd of May in that year.

Michelangelo made designs to meet this plan, but whether the tombs were still detached from the wall does not appear.

Standing inside the sacristy, it seems impossible that six statue-portraits and six river-gods on anything like a grand scale could have been crowded into the space, especially when we remember that there was to be an altar, with other objects described as ornaments--"gli altri ornamenti." Probably the Madonna and Child, with SS.

Cosimo and Damiano, now extant in the chapel, formed an integral part of the successive schemes.
One thing is certain, that the notion of placing the tombs in the middle of the sacristy was soon abandoned.