Argo Navis
The final breakup and abolition of Argo Navis was proposed by Sir John Herschel in 1841 and again in 1844. Despite this, the constellation remained in use in parallel with its constituent parts into the 20th century. In 1922, along with the other constellations, it received a three-letter abbreviation: "Arg". The breakup and relegation to a former constellation occurred in 1930 when the IAU defined the 88 modern constellations, formally instituting "Carina", "Puppis", and "Vela", and declaring "Argo" obsolete. Lacaille's designations were kept in the offspring, so "Carina" has α, β, and ε; "Vela" has γ and δ; "Puppis" has ζ; and so on. As a result of this breakup, Argo Navis is the only one of the 48 listed by Ptolemy in his "Almagest" no longer officially recognized as a single constellation.