16 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



tary 

 Group. 



afield, upon the ground, water, or trees, and as a rule have no fixed domi- 

 cile, except at the brooding time and during winter. These principal groups 

 are subdivided into seven secondary groups, sections or suborders. 1 

 The four tribes comprising the Sedentary spiders are named strictly 

 from the chief characteristics of their spinningwork, viz.: the Orbi- 

 telariee, from their orb shaped web ; the RetitelariaB, from their 

 net like web or snare of crossed lines ; the Tubitelarise, from the tubular 

 web which they spin, and from the opening of which, in some species, a 



close textured snare spreads out in 

 all directions ; the Territelarise, from 

 the silken cylinder with which the 

 typical species line their burrows 

 in the ground. 



The Wandering spiders include 

 three tribes, which are conspicuous 

 by their ordinary independence of 

 snares for the capture of prey, and 

 have been named from certain pe- 

 culiarities of motion. The 



Laterigradse have legs so 

 ing Group . 



inserted as to permit a 



motion sidewise, as well as forward 

 or backward. For this reason La- 

 treille called them also Crab spiders. 

 The Citigradse include those species 

 that keep chiefly to the land and 

 water, upon which they run with 

 great rapidity. The Saltigradse, or 

 vaulting spiders, are named from 

 their hopping movement in ordi- 

 nary progress. The individuals of 

 these three tribes are almost equal- 

 ly entitled to be called citigrades, 

 for they all move swiftly, but the 

 Citigrades technically so termed are 



PIG. 2. Territelariae : Eurypelma Steindachnerii Ausserer. habitually running Spiders, keeping 



closely upon the ground, while the 



Laterigrades and Saltigrades are arboreal, habitually dwelling upon plants 

 and vertical surfaces. The three are also quite distinct in their structure, 

 and the systematic position of any one, as far as above indicated, can com- 

 monly be told by a glance at the form. 



1 Thorell uses the term " suborders " in his European Spiders for these principal groups, 

 but adopts the term "sections" in his "Descriptions of the Aranese of Colorado" (Bulletin 

 U. S. Geological Survey, Vol. III., No. 2, page 477, note), and still later the name tribe (tribus). 



