The sac spiders of the family Clubionidae have a very confusing taxonomic history. Once this family was a large catch-all taxon for a disparate collection of spider

Spider

Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

s, similar only in that they had eight eyes arranged in two rows, conical anterior spinnerets that touched and were wandering predators that built silken retreats, or sacs, usually on plant terminals, between leaves, under bark or under rocks.