They were inaccurate. They may have been the basis for the drawings in many texts, but his theories were almost universally rejected. Creationists trot him out as if anybody has taken his theories seriously for the last 100 years. As I said with the text I have, the pictures are based on Haeckel, but the text clearly states he was wrong. I have no reason to believe that this was different in the vast majority of texts. And my text came out in 1993.