Mensa is a Southern Hemisphere constellation otherwise known as the Table. It is one of fourteen new constellations created by French astronomer Abbe Nicolas Louis de Lacaille (Wikipedia) in the 1750s, from his star catalog observations from the Cape of Good Hope and published posthumously in Coelum Australe Stelliferum in 1763. Mensa remains one of the 88 modern constellations defined by the International Astronomical Union (Wikipedia).
Mensa (abbrev. = Men; genitive = Mensae) covers 153 square degrees or 0.37% of the celestial sphere making it the 75th largest constellation. It contains 22 stars brighter than apparent magnitude 6.5, the brightest star being Alpha Mensae.