Two genera of trap-door spders from California

While trap-door spiders have long excited general interest, as a group they are very imperfectly known. This is due largely to the fact that their subterranean habits enable them to escape ordinary observation and to have, as a consequence, relatively poor representation in collections, both as to species and as to number of individuals. It is also unfortunate that in many cases only the females are known, while it is the secondary characters of the male that are most readily used in discriminating species and often genera.