@carloslebaron,
GeoffROY St Hillaire really did NOT develop any theory except in sense that it was a "Hypothesis" without substance. He "believed" in a "Saltation means of transmutation " here entire orders could develop from previous orders. However, he was NOT a subscriber to common descent.
A theory in science is a lot more substantive than collection of "ideas" with no means of testing or providing evidence.
That was ST Hillaires hypotheses.
The theory of natural selection, like all theories passes the two prt test in that
1ALl facts support the theory
and
2No fcts refute it.
St Hillaires hypothesis , which has a basis of saltation and no common ancestry at its source , has not been supported in evidence (Punctuted Equilibrium, though not a "saltation" hypothesis, has been shown to be basis-free" wrt evidence from Gould nd Eldgredge' own field sites from which they derived their hypothesis. St Hillaire had not done NYWHERE near the amount of work that Gould and Eldredge had done in his own pronouncement.
The
One thing that Darwin did, after his 2nd edition of the "Origins...",he acknowledged all those who had developed "trnsmutationl ideas" prior to his ownw ork. Darwin acknowledged these workers and then calmly dismissed most by showing qhere he was different.
Darwin had differences with Etienne Geoffroy ST Hillaire in the Saltation and "no common descent: res , but he also AGREED with Isidore.G St Hillaire about the correlation of homologous structures and also with Etienne G t Hillaire on homologous part (but with different aspects of descent with modification).
So your point seems to me to only reside with a concern that Darwin make( proper citation of sources for work done by others. I never declined that aspect ,(nor has he when Hooker reminded Darwin that such citations were "missing" from his first edition) but Ive never declined either, to "throw off' the mass of work and the resulting theory of natural selection which is solely the product of Darwin mind. (It appears that most all of the attempted belittling of Darwins work seems to fit as a cornerstone of the religious Fundamentalists who merely wish to to argue that Evolution by naturl selection is invalid).
Each month , new data and evidence appears that supports the general theory and nothing shows up to even begin to support anything else.
Hwen it comes down to it, Darwin probably owes more for the structure of his theory to one R E Grant, yet Darwin fails to acknowledge Grant's ideas
The really interesting development of the Origin, as a SET of books, not just one, can be really seen in Morris PEckham's Variorum text which lays out all the modifications to the "Origins..."" that Darwin made within each edition, an which defined each edition as the book grew by almost one hundred pages