This image was chosen by Ithiel Town for a commemorative coin that was produced for the 200th anniversary of the founding of New Haven, CT. The medallian is propped up on a table beside Town in his 1839 portrait. The image features St. George (patron saint of England) slaying the dragon (often a symbol of the devil or our base instincts), and appears to be an exact replica of an English coin of the early 19th century. Although the image of a dragon being slayed is also associated with philosophical Alchemy, other Christian images in the portrait and the connection with the English coin argue for a Christian reference, though both are possible.
It's also difficult to understand why Town chose a replica of an English coin for the commemoration of an American town.