This is a late 19th Century Naval Ensign's shoulder strap. During the Civil War anchors on Navy shoulder straps generally had stocks (across bars) set at angles to the shanks (center pole). The stocks of
postwar straps are set at 90-degree angles to the anchors' shanks as in the above example.
The firm of William H. Bellis listed 1849 as a found date, but adds for the firm do not appear until 1888. It is common for firms to list founding earlier dates than other evidence supports. Bellis imported Naval items from the English firm of Joseph Starkey.
This is an example of the typical Civil War Navy period shoulder strap from the Schuyler, Hartley and Graham catalog.