THE NORTH AMERICAN SPIDER FAUNA 265 



distribution is largely limited to the extreme southern and south- 

 western states. A few archaic types still persist in the Southeast 

 (Hypochilus), in the Southwest (Plectreuridae and Diguetidae, 

 Atypoides and Aliatypus), and even in the Northwest (Hexura and 

 Antrodiaetus). Although the general character of the North Amer- 

 ican spider fauna is now known, many of the details are still vague, 

 and can be clarified only by considerable exploration of little- 

 known regions. 



The following arrangement of spider families and higher sys- 

 tematic divisions, largely based on the works of Eugene Simon, was 

 adopted for use in this volume. Only those families preceded by the 

 asterisk (*) have no representatives in the North American fauna. 



Suborder MYGALOMORPHAE 

 ATYPOIDEA CTENIZOIDEA 



(The Atypical Tarantulas) (The Typical Tarantulas) 



* Liphistiidae * Paratropididae 



(*Heptathelidae) (*Pycnothelidae) 



Mecicobothriidae * Migidae 



(Hexuridae) Dipluridae 



Accatymidae Ctenizidae 



(Brachybothriidae) * Barychelidae 

 Atypidae Theraphosidae 



Suborder ARANEOMORPHAE 

 HYPOCHILOIDEA Dinopidae 



(The Four-Lunged True * Eresidae 



Spiders) Oecobiidae 



Hypochilidae * Psechridae 



* Tengellidae 



FILISTATOIDEA * Acanthoctenidae 



(The Filistatids) Zoropsidae 



Filistatidae fT" \~A x 



(Amaurobndae) 



DICTYNOIDEA PLECTRUROIDEA 



(The Typical Cribellate (The Primitive Hunters 



Spiders) and Weavers) 



Uloboridae Plectreuridae 



