http://www.linns.com/howto/refresher/paquebot_20041213/refreshercourse.asp?uID=

"K.N.S.M." in the cancel stands for Koninklijke Nederlandsche Stoomboot Mij. (Royal Netherlands Steamship Company). The "M/S" indicates the ship's classification as a motor ship. Pygmalion is the name of the ship.

In addition to "M/S" for motor ship, other types of vessel designations used in ship's handstamps are "M/V" for motor vessel, "S/S" for steamship, "S/T" for steam tanker or steam turbine, "M/T" for motor tanker, "M/F" for motor ferry, "S/V" for sailing vessel and "TES" for turbo electric ship.