Dear Gino,

Thank you for the additional images and your patience. The apprised object is a watercolor with the measurements of 19" x 27". The drawing depicts a mermaid attacked by an octopus. The drawing is signed in the right corner by the Dutch artist Henri van der Stok (1870-1946). On the left side of the paper is damaged by water.
An estimation would be between 100 to 200 USD.
This estimation is based on actual recent past recorded auction sales of comparables. Retail "asking prices" can be higher and vary.

With best regards,
Georg