[3] These ecribellate, haplogyne spiders build haphazard webs under rocks and dead cacti.

Unlike the sicariids, scytodids, diguetids, and segestriids, to which they are most closely related, they have eight eyes.

They differ in their eye arrangement and in having the femurs on the first pair of legs bowed.

Along with Filistatidae, they have the largest venom glands of all spiders relative to body size.

[5] As of April 2019[update], the World Spider Catalog accepts the following genera:[6]