De l'espèce et de la classification en zoologie. Traduction de l'anglais par Félix Vogeli. Édition revue et agumentée par l'auteur.

While Agassiz often wrote in general terms regarding his virulent opposition to Darwin's theory of evolution by natural selection, he provided his scientific rationale for that opposition only in an appendix to the French translation of his Essay on classification: Part 3, Chapter 7: Le Darwinisme. - Classification de Haeckel. Digital facsimile from the Biodiversity Heritage Library at this link. See Morris, P.J., "Louis Agassiz's additions to the French translation of his Essay on Classification," Journal of the History of Biology, 30 (1997) 121-134 . Morris's English translation is available from athro.com at this link.