The Merkur mark shows the winged head of Mercury with two staffs surrounded by snakes above the Villeroy & Boch banner. Mercury is referred to as the god of commerce. The stamp was registered by the company at the Imperial Patent Office on March 18, 1876 after a trademark protection law came into force in Germany on May 1, 1875. In addition to the tower mark (=embossed mark), the Merkur mark (=stamp mark) is the most important trademark of the company.
Dating: Below the so-called scrollwork banner with the inscription "Villeroy & Boch" there are 2 semicircles in which the name "Mettlach" is entered in an arc. This is followed by a jagged semicircle. Between 1890 and 1909 dating was done using the 10-spikes system. The number and position of dots added to the spikes indicate the exact dating. However, there is no coding by dots for the year 1910.
Instead, the Mercury mark below the jagged arc contains the copyright "LEGALLY-PROTECTED". Furthermore, the addition "Made in Germany" suggests that the object was intended for export.
Source: https://mettlachbuch.de/keramik/villeroy-boch-mettlach-stempel