Spiders and Their Near Relatives 



C. Tail stout and armed with a sting at the end; first pair 

 of legs not greatly elongated; a pair of comb-like ap- 

 pendages on the lower side of the second abdominal 

 segment in the adult. (Scorpions) P. 21. 



Scorpionida 



CC. Tail slender, usually whiplash-like, without a sting; 



first pair of legs much longer than the others; without 



comb-like appendages on the abdomen. 



D. Body of minute size being less than one tenth inch 



in length (Micro-whip-scorpions) P. 13. 



MlCROTHELYPHONIDA 



DD. Body of moderate or large size. (Whip-scorpions). 

 P. 16. Pedipalpida 



BB. Abdomen without a tail-like prolongation. 



C. Palpi with pincer-like claws. (Pseudoscorpions) P. 39. 



PSEUDOSCORPIONIDA 



CC. Palpi without pincer-like claws. 



D. Abdomen joined to the thorax by a slender stalk; 

 front legs greatly elongated and with whiplash-like 

 tarsi. (Whip-scorpions) P. 16. Pedipalpida 



DD. Abdomen broadly joined to the thorax. 



E. Legs usually very long and slender; thorax not 



distinctly divided into three segments. (Har- 



vestmen) P. 53. Phalangida 



EE. Legs moderately long; head distinct from thorax; 



thorax distinctly divided into three segments. 



P. 32. Solpugida 



AA. Abdomen unsegmented. 



B. Abdomen joined to the cephalothorax by a short, narrow 

 stalk. (Spiders) P. 39. Araneida 



BB. Abdomen fused with the cephalothorax. (Mites) P. 8. 



ACARINA 



Order MlCROTHELYPHONIDA* 



The Micro-Whip-scorpions 



The tiny creatures constituting the order Microthelvphonida 

 (Mi-cro-thel-y-phon'i-da) bear striking resemblance in the form 



This order was established under the above name by Grassi ('86). Later Thorell 

 changed th.' name to Palpigradi; but this latter name cannot be justly accepted, although it is 

 shorter and equallyappropriate- 



13 



