Depiction of a heptereme, a warship larger and considered more seaworthy than the trireme or bireme (galleys with three or two rows of oars, respectively). With a ramming horn and a figurehead of Athena, and a single mast with furled sails. Title is printed in the lower margin, along with artist attribution.
The title may refer to an episode recorded by Plutarch, when the fleet of King Pyrrhus was making the crossing from Greek to Tarentum in 280 B.C. The fleet was heavily damaged during a spate of heavy weather, but the large ship--believed to be a heptreme--that served as Pyrrhus' flagship--was better able to deal with the dangerous seas than the smaller vessels.
This image is an artist's conception of what that vessel might have looked like, as opposed to a ship portrait proper.
