One shouldn’t really talk about those Fonteian coins as I was doing yesterday without adding in this coin of Q. Lutatius Cerco (quaestor, but whose quaestor?). It was minted between the two other issues with full ship reverses. It is given by Crawford a historical not legendary interpretation. It’s seen as a celebration of the navel victory of C. Lutatius Catulus in 241 BC. It clearly inspired by the first Fonteian coin and in turn inspires the design of the second. The element it adds to the design are the overlapping shields above the oars. This is a feature also seen on sculptural reliefs. The reason this seems important to me is that the supposed doliolum of symbolic importance on the stern of the second Fonteian coin, looks to me as just another shield added for decoration:
On some specimens like this one that haven’t been rubbed smooth it even seems to have the same line decoration. I’ve not been able to find a parallel of a shield placed in this position on a ship depicted in other media. (Largely because looking for one is a distraction from the book!)
I should have also brought the Lutatius coin into my previous discussion of prow stems.
Postscript. Do those two big stars on Roma’s helmet recall the dioscuri/penates? Notice the stars over the Penates heads on Mn. Fonteius’ coin.
Notice the dioscuri caps in front of the prows on this rather rare variation on the standard design of the as. There is a victory palm above. Perhaps further evidence that there is some association between navel victory (victories?) and the Dioscuri?
Update 4/29/14: Compare the placement of the rear shield on this representation: