Spiders and Their Near Relatives 



resembling the abdominal segments in the degree of their dis- 

 tinctness. This is doubtless a very generalized feature. 



The abdomen consists of ten segments, all of which are free. 

 The beak, which bears the mouth at its tip, projects forward 

 from between the basal segments of the pedipalps. There is a 

 pair of eyes near the middle line on the front part of the head, 

 and one or two vestigial eyes on each side of the head (Bernard 

 '96). The chelicerae are two-jointed and chelate; compared to 

 the size of the body, they are larger than in any other arachnids; 

 and they are the only ap- 

 pendages fitted for crushing 

 the prey. "Observers re- 

 late that, in order to bring 

 the beak up to the wound 

 in its prey, the animals 

 work the chelicerae with a 

 sawing motion, holding 

 tight with one to drive 

 the other deeper in." A 

 peculiarity of these che- 

 licerae is that the second 

 segment is articulated to 

 the lower side of the first 

 segment, so that the pincers 

 open and shut dorsoven- 

 trally. In some forms each 

 chelicera bears on its upper 

 side a remarkable sensory 

 appendage, which is called 

 the JJ age Hum; this varies in 

 shape greatly in the differ- 

 ent genera; it has been thought that this organ is possessed only 

 by males, but (Bernard '96) states that this is not certain. The 

 function of the flagellum is unknown. The pedipalps are leg-like 

 in form, but without claws. They bear no masticatory ridges; 

 and it is evident that their chief function is that of feelers. At 

 the tip of each pedipalp there is an invaginated sense organ 

 (Bernard '96); these were formerly supposed to be suckers for 

 clinging to objects. The first pair of legs have lost their locomotor 

 function and doubtless resemble the pedipalps in function; their 



Fig. 37. EREMOBATES CINEREA 



(after Putnam) 



33 



