Kley was a German caricaturist, editorial cartoonist and painter. Much of his imagery focused on fantastic scenes depicting humorous and often disturbing imagery, some of which I've posted below. I found the picture above of the giant catterpillar attacking a woman especially creepy.
Toy trains animated like snakes.
A man having his insides pulled open by a crowd of miniature people.
People climbing out of the artist's skull and absorbing into the drawing surface.