Thanks! Are there (or more importantly, were there then) any restrictions on where a validly published description can appear? I know with botanical publication newspapers are not admissible as formal publications, presumably because they are not considered permanent enough. What the Literary Gazette would count as, I don't know.
The Code requirement is that a publication "must be issued for the purpose of providing a public and permanent scientific record".
A newspaper might indeed be regarded as published for the purpose of providing immediate information rather than any permanent record; but, in birds at least, I know of of no cases that are currently treated this way. Some bird names are treated as available from outlets that I would regard as quite clearly less permanent that the Literary Gazette (things like this:
https://trove.nla.gov.au/newspaper/article/63664143 ). The Literary Gazette at least produced an index to each of their volumes: to me, this demonstrates an intention to make their content permanently searchable and retrievable.
In 1990, the Commission conserved the spelling of the genus-group name Semioptera Gray 1859, which had usually been taken from PZS and was threatened by an earlier publication as 'Semeioptera' in the Literary Gazette. They did not do this by ruling that the Literary Gazette was an unacceptable venue; what they did was to place the name on the Official List as dating from its publication in the Literary Gazette, with a ruling under the Plenary Powers to the effect that 'Semeioptera', as used there, was an incorrect OS:
https://www.biodiversitylibrary.org/page/12230496 .
In 1997, the SCON (Schodde & Bock) tried to obtain a global suppression, by the Commission, of all the Gould names introduced in the Literary Gazette and the Athenaeum, and which had been later published in PZS:
https://www.biodiversitylibrary.org/page/12446416 . This failed:
https://www.biodiversitylibrary.org/page/34357821 .
PS - Re. "Are there (or more importantly, were there then)": only the current edition of the ICZN has any force, so the only thing that really matters is "Are there". (This is
ICZN 86.3.)