But if you look at the text
here Juin 1831. I am not sure if it is always
Plate 1, 2, 3 Livr 1,
Plate 4, 5, 6 Livr 2 etc.
At least with the Gould hummingbird plates it is not like that. But Lesson refered to the Bulletin in Illustration de zoologie.
But the meaning of the dates appearing at the end of each text is not explained in the work, and they might very well indicate a date of writing, rather than a date of publication. (I.e., they are probably best seen as "Not before" dates.)
- According to
Bibliogr. France of 4 Feb 1832 --
https://books.google.com/books?id=QbEisyJoLvgC&pg=PA70 --, a prospectus had been issued, announcing the start of this work's publication for March 1832. This is very strong evidence against the publication of any part of the work in 1831. The actual publication of Livr. 1 was not reported before 14 Jul 1832 --
https://books.google.com/books?id=QbEisyJoLvgC&pg=PA392.
- As you say, Lesson quoted the
Bulletin description of the sunbird in the text of the
Illustrations, citing a correct page number ("
Bull. des Sc., t. XXV, p. 242.") which he could presumably not have known if this had not been published yet. Additionally, his note in the
Bulletin was titled "Illustrations de Zoologie; par RP Lesson. 1e décade:
Ms.", and he noted there "L'auteur a fait exécuter une suite de vélins par l'habile peintre d'hist. nat., M. Prêtre, et
désirerait les publier: à ce suiet,
il lui importerait peu qu'ils soient gravés et mis au jour en Allemagne ou en Angleterre [...]" --
https://biodiversitylibrary.org/page/4441029. This is explicit indication that he was reporting there about a manuscript which he wished to publish (i.e., not an already published work); and about plates that had been painted but had still to been engraved (i.e., not a work that was (even in part) nearing publication).
- Gould published his plates as he produced them, then reorganized them so that they would ultimately follow a systematic sequence (which, not unexpectedly, differed from the publication sequence). In some other works by Lesson, the final sequence of the plates in the work was imposed by the text, and is known to have differed from the sequence of publication as well. (
La Coquille may be the best documented case, because the detailed plate content of each livraison of this work was announced in Férussac's
Bulletin all along the publication process, thus is known for sure.) However, no systematic or logical sequence of any kind is present in Lesson's
Illustrations de zoologie (e.g., the sunbird in question is preceded by a shell, and followed by a beetle...), thus there is no apparent reason to think that Lesson might have reorganized his plates a posteriori in this case.
- At least one point in the publication process of the
Illustrations can be verified directly: the detailed content of livr. 1-12 was published in 1834 in
Allgemeine Literatur-Zeitung https://books.google.com/books?id=BipRAAAAYAAJ&pg=RA3-PA481. Checking this confirms that the first 12 livraisons of the work, indeed, included the first 36 plates of the final book and their text.