Different versions of the British lion passant are often used on silver items of 19th century American silver from New York state.
Many Canadian marks also included different styles of lion marks.
In England the lion passant indicates a fineness of .925 or sterling. On American and Canadian marks it has no meaning at all.
John L. Vestervelt was born on a farm near Newburgh in 1826. In the nearby town of Walden he served his apprenticeship. I checked a map and Monroe, New York, is just southwest of Newburgh.

Pat.