Nature's artforms, with alpha channels, free for the remixing

Spot Draves has released a bunch of Ernst Haeckel's Kunstformen der Natur (Artforms of Nature) as Creative-Commons-licensed, high-resolution scans in PNG format, with painstaking alpha transparency channels that allow you to easily composite them onto other images. Haeckel was the naturist who stated that "ontogeny recapitulates phylogeny" -- that foetuses step through their evolutionary history in the womb. It turned out that he was kind of making that up and faking his evidence, but he sure drew pretty pictures, and the meme's got legs. Well, first it had a tail, then it had legs.