n8 AMERICAN SPIDERS 



with a conductor of the embolus a shield for the protection of the 

 delicate tube found in none of the typical tarantulas and apparently 

 similar to that found in the true spiders. The epigyna of the females 

 all agree in having four primary seminal pouches, whereas in almost 

 all higher My galomorphae and true spiders there are only two. 



The atypical tarantulas are hardy creatures that live much far- 

 ther north in the United States than any of the typical tarantulas. 

 Some of the folding-door tarantulas are common in our Pacific 

 Northwest, and extend even into British Columbia and Alberta. 

 In Europe At y pus is found in England, and the same species occurs 

 in Denmark, a location that would place it above the 50th parallel 

 north. In the United States Atypus is uncommon in the north but 

 has been taken in Massachusetts and Wisconsin, well above the 4oth 

 parallel. 



Liphistiids. The liphistiids are the most primitive of all living 

 spiders, still maintainng the appearance and probably the funda- 

 mental structure of their ancient Paleozoic forebears. They occur 

 only in the Orient, but are reviewed here for comparison with the 

 other atypical tarantulas, which are predominantly American. Li- 

 phistius lives in hilly districts in the Malay States and adjacent 

 Sumatra, where five species occur, and in similar situations in Burma 

 and northern Indo-China, each of which has a single species. The 

 genus Heptathela comprises a single species from the southernmost 

 Japanese island of Kyushu and the Luchu Islands, and one from 

 Shantung, China. 



A series of tergites, all of which are conspicuous, hardened 

 plates set with rows of erect setae, is a striking feature of the 

 liphistiids. All twelve primary abdominal segments can be recog- 

 nized by external tergites in Heptathela, whereas at least nine are 

 distinct in Liphistius. The generalized condition of the abdomen 

 is further seen in the median position of the spinnerets. The great 

 space between them and the anal tubercle represents those reduced 

 segments behind the sixth that in higher spiders are completely 

 incorporated into the tubercle. Four pairs of spinnerets are pres- 

 ent, but the median pairs are greatly reduced in size. The lateral 

 spinnerets of Liphistius are short, thick, fingers, with a large basal 

 segment and an apical portion that is divided transversely into many 

 small rings, thus said to be multisegmented. In the other atypical 

 tarantulas, the spinnerets have shifted much farther back, but in 



