CHAPTER V: 



Order ARANEIDA (Ar-a-ne'i-da) 

 The Spiders 



The order Araneida includes only the spiders. These differ 

 from other Arachnida in having a sac-like, unsegmented, abdomen, 

 which is joined to the cephalothorax by a slender pedicel (Fig. 

 206). In a single genus, Liphistius, which is found in Sumatra, 

 the dorsal wall of the abdomen is segmented. 



The segments of the cephalothorax are closely united so that 

 none are distinct. The chelicerae are usually uncate, that is the 

 claw is folded back into a groove in the basal segment, like the 

 blade of a pocket-knife into the handle (Fig. 207) ; but sometimes 

 they are chelate, there being a prolongation of the first segment 

 which is opposed to the claw, thus forming a pincer-like organ 

 (Fig. 208). The pedipalps are more or less leg-like and are fur- 

 nished in the larger number of families with more or less distinct 

 endites (Fig. 209 en); in the male the terminal portion of the 

 pedipalp is modified into an organ for the transference of the 

 seminal fluid. The four pairs of legs are all fitted for walking. 

 There are usually eight eyes; but in several families and in isolated 

 genera of others the number is reduced to six; rarely there are only 

 four or two, and some cave species are eyeless. Two pairs of 

 abdominal legs are preserved in a more or less two-branched form 

 and serve to carry the outlets of the silk glands (see p. 134); 

 these legs are termed the spinnerets. 



The order Araneida includes two suborders, which have been 

 named by E. Ray Lancaster, the Mesothela? and the Opistho- 

 thelse respectively. These are distinguished as follows: 



Suborder MESOTHEL/E (Mes-o-the'lse) 



This suborder is not represented in our fauna; but it is briefly 

 discussed here on account of its great scientific interest. It 



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