Spiders and Their Near Relatives 



Order PEDIPALPIDA* 



The Whip-scorpions 



These strange creatures are found in our country only in the 

 extreme southern part, they being tropical animals; but they are 

 distributed from the Atlantic to the Pacific. In their general 

 form they bear some resemblance to scorpions; but they can be 

 easily distinguished from scorpions by the form of the pedipalps, 

 of the first pair of legs, and of the postabdomen. 



The common name whip-scorpions was doubtless suggested 



by the slender caudal appen- 

 dage of the Thelyphonidae 

 (Fig. 14); but it is almost as 

 appropriate for the forms 

 that lack this appendage, as 

 they have the tarsi of the 

 front legs broken up into 

 many small segments, which 

 gives this part of the leg 

 a whiplash-like appearance 

 (Fig. .8). 



These arachnids are of 

 moderate or large size, none of them 

 being minute like the Microthely- 

 phonida. The abdomen is segment- 

 ed, and distinctly separate from the 

 thorax. In one family the carapace 

 is divided by transverse sutures; in 

 the other two families it is not so 

 divided. The chelicerae are two- 

 jointed and uncate; that is the second segment is claw-like and 

 folds back upon the end of the first segment. A remarkable 

 feature, in some members of the order if not all, is that the chelic- 

 erae are attached to the head by a thin membrane in such a way 

 as to be capable of being retracted into the head for a considerable 

 distance (Laurie '94). The pedipalps are very stout and are six- 

 jointed; they present the three types of claws, one in each of the 



* The original form of this name was Pedipalpi, a family name proposed by Latreille (1806); and 

 this forji is still r.-tained by many writers even though they rank the group as an order. 



16 



Fig. 14. MASTIGO- 

 PROCTUS GIGANTEUS 



