Date of publication
I wasn't sure about the date of publication, so I contacted the IOC World Bird List. Here is their reply:
The date associated with Megapodius cummingi Dillwyn, 1853 is correct.
While is true that the imprint date associated with the description of this species in Part 19, no.226, p.119, pl.39 of the Proceedings of the Zoological Society of London is “1851” the date of delivery or actual publication of this work was not until July 26, 1853. Where that date of imprint and the date of publication (if known) are different, the latter prevails in zoological nomenclature.
In many of the earlier issues of the PZS, the imprint and publication dates differ. A nice set of tables of these differences for the earliest issues of the PZS was published in the PZS in 1893. Here is the page from that issue of the PZS that is relevant to this particular taxon:
The comprehensive way to cite this in zoological nomenclature is to include the “incorrect” imprint date in quotes and brackets.
Megapodius cumingii Dillwyn, 1853 ["1851"]