328 NATURE-STUDY REVIEW [15:6— Nov., 1919 



thing more of the spiders' house building proctivities later, but first 

 wish to relate a few interesting things of the spiders themselves. 

 If we are disposed to fear spiders we should probably show 

 consternation if the great Bird Spiders of South America were 

 common and entered our dwelling as do the harmless species of 

 our more favored North. It is comforting knowledge for the more 

 timid of us, that none of our northern spiders inflict venomus bites. 

 The Tarantulas it is true are much feared in the parts they inhabit, 

 not alone because they are large and formidable looking, but be- 

 cause it is well known that they do possess well developed poison 

 glands, and will bite if molested. The posion however will do no 

 more than cause an irritation and it is well to remember that the 

 bite of the black fly will produce a like effect. There is but 

 one spider in the United States that is known to he actually dangerous 



Entrance to nest of a trap-door spider 



and that is known as the Hour-glass spider or the Black Widow 

 of the South. 



In Texas, California and other regions of the Southwest a won- 

 derful group of very large spiders are found that are known as the 

 Trap-door spiders, or Ctenizinae. 



Armed with a powerful pair of clawed appendages, that scientific 

 men call chelicerse, these big fellows dig tunnels in the earth. 

 They roll the loosened material up in small balls and fling it out 

 of the burrow with their hind legs. That you may say is not very 

 remarkable. Other animals dig burrows in the earth. The chip- 

 munk makes a very neat one. But our spider has not yet finished 

 his work, when the tunnel is completed to his satisfaction he, 

 mason-like rough coats its walls with a coat of saliva, he then 

 proceeds to line it very comfortably with a soft drapery of fine 

 silk. Has he brought his task to constmimation then? Not he: 

 shall his dwelling be doorless, exposed to the uncertain outside 

 world ? Oh ! no ! Our spider with fastidious exactness fits to his 



