Monstrance portée par deux anges
France, XVe siecle. Argent doré.
Legs Nathaniel de Rothschild en 1901, Cl. 14082

Which can be roughly translated as:

Monstrance carried by two angels
France, 15th Century. Gilded silver.
Bequest of Nathaniel de Rothschild in 1901, Cluny catalog number 14082

More information on reliquaries can be found at Wikipedia and at the Metropolitan Museum of Art site.