This is Duncan & Miller's Pall Mall Line Solid Back Medium Swan (#30). It measures 3.75" tall by 4.75" long. It was produced circa 1920's - 40's.
"Pall Mall, by Duncan, has that deep, clear, flawless beauty, which is essential to the plain simple designs of the 'modern' style. As such, it lends itself to a myriad of new uses--for home decoration, for the table, for flowers." -- excerpt from a Duncan catalogue (c.1945)
This series was designed by their premier designer Robert A. May. This swan is in excellent condition. No chips, or cracks, and only two small flea bites on the bottom along the seam line. There is some wear on the bottom with minor scratching and there are a couple of bubbles in the glass which are typical of glass produced during This time line.