Arachnids, including ticks (Ixodes ricinus, 9); mites (red velvet, Trombidium holosericeum, 3 and scabies, Sarcoptes scabiei, 11); a harvestman (Phalangium opilio, 2); and a pseudoscorpion (Chelifer cancroides, 1). Also visible is a water bear (Macrobiotus ursellus, now known as Hypsibius dujardini, 12), even though it is not an arachnid. Illustration from De gelede dieren, by Dr. Samuel Constantinus Snellen van Vollenhoven, the entomologist at the Natural History Museum, Leiden, Netherlands, in 1868.