There were two kinds of zoological pictures

Some showed an animal in its natural environment; for example from Zoological Imagery by Lehmann: The Condor, the Crocodile or the Giant Snake.

Others focused on anatomy; for example from Pictures of Animal Anatomy by Lehmann and Brass: “A Comparative Study of the Skull and Teeth” (and the same for arms and legs) or “the Skeletons, Spine and Bones for swimming of the Frog and the Perch.”