The Public and Private Life of Animals (1877) by J. Thomas is a satirical book about animal life from the 19th century. My favorite thing about this book are the incredible illustrations. I can't get over how beautifully drawn and compelling they are.
These drawings are by caricaturist J. J. Grandville, and show animals in human clothing, engaged in conversation, political acts, and dream-like scenes that feature Hieronymus Bosch-like creatures. I hadn't heard of Grandville before coming across this book. He's now at the top of my list of artists to research more about.
On the Public Domain Review, you can read the book in its entirety. You can also simply browse through the stunning illustrations, below the book. I'd love to have a physical copy of this!
See also: FrEEKs! is a book of wonderfully weird mutants and creatures by cartoonist J.R. Williams