In a horizontal rectangle with cut corners is a Dutch maker’s mark for; Gebr. (Brothers) Fa (Firm) Roelfsema also known as J.H. Roelfsema, registered in the city of Winsum in the province of Groningen, during 1864/1910. As far as I can see no official Dutch hallmarks or export/import marks and pseudo mark only. Sold directly by the brother’s without hallmarking to a foreigner/tourist and done probably to avoid duty tax. For more info see: viewtopic.php?f=5&t=28590
And yes, Qrt.S is right about the use of this tongue; luiertang
or napkin tongue.Tongues of which the ends of the legs consist of two opposing long ribbed surfaces. Some believe that those tongues were used by the nurse or mother to dispose of dirty diapers. Some believe the tongue was used to hold/clamp the umbilical cord of the newborn baby (clamping is followed by cutting of the cord) and often we can find a wrapped baby in the abdominal cavity of the Stork, here we have a fish, sometimes we see the stork standing on a turtle; symbol for a long life.