Back in the second century, Claudius Ptolemy wrote the Almagest, an astronomical (in the literal sense) treatise on the heavenly constellations. In it, he identified 48 constellations, including Andromeda, Aquarius, Cygnus, Orion, Lupus (it's never Lupus), Ursa Major and Canis Major. He missed one.
Thanks to Ash78, commenting on the guy who stole his date's Ford Focus while they were at the movies, we now know that there's a constellation Ptolemy overlooked. It's an important one, easily seen by the naked eye. You just need to know where to look. Thank you, Ash, for pointing it out, though we've known for a long time it was out there, somewhere.