Ernst Haeckel (1834-1919) was a German scientist and illustrator, and an ardent supporter of Darwin. He was also a proponent of scientific racism, but looking at these I think we can just about let him off. His work is now in the public domain, and much of it can be found at Wikimedia Commons, including the whole of Art Forms in Nature (1904). Just don't expect any kind of 'scientific' accuracy.
Hunger by Knut Hamsun
7 hours ago