Spiders and Their Near Relatives 



prey, and the last four, as legs; but there is considerable lack 

 of uniformity in this respect. Owing to this lack of uniformity 

 in the function of some of the appendages in different orders 

 some writers designate the six pairs of appendages by numbers; 

 but the older authors gave special names to the first and second 

 pairs, and termed the last four pairs legs. The older nomen- 

 clature is so well established that it does not seem wise to attempt 

 to change it, notwithstanding that in one order the second pair 

 of appendages function as legs, and in another order, the third 

 pair of appendages function as feelers. 



The first pair of appendages are termed the chelicerce (che- 

 Iic'e-rae). They are situated in front of the mouth; all other 

 appendages are postoral, except perhaps the second pair. 



The second pair of appendages are the pedipalps (ped'i- 

 palps). These are situated immediately behind the mouth, or 

 one at each side of it. They are always more or less leg-like 

 in form; and in the Microthelyphonida they function as legs. 



Following the pedipalps are the four pairs of legs. In the 

 Pcdipalpida, the first pair of legs function as feelers. 



Usually the basal parts of the pedipalps bear masticatory 



Fig. 10. TARSAL CLAWS OF A SPIDER 



Fig. it. A CHELA 

 oi \ PEDIPALPOF 

 A SCORPION 



ridges for crushing the prey. Sometimes the 

 crushing organ is a distinct sclerite borne 

 by the basal segment of the pedi- 

 palp; it is then known as an endite. 

 Masticatory ridges or endites are sometimes 

 borne by the first or the first and second pairs of legs. 

 The last segment of an appendage may bear claws, which 

 resemble more or less the tarsal claws of insects. (Fig. 10.) In 

 other cases the last segment itself is claw-like; in this case a pincer- 



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