CHAP. XVI 



PALPIGRADI SOLIFUGAE 



423 



genital operculum is complicated, and is situated beneath the 

 second abdominal segment. 



Since 1885 several other species have been discovered in 

 various parts of the world. Two American 

 forms possess three pairs of lung-sacs on 

 segments 4, 5, and 6 of the abdomen. 

 Eucker^ has suggested for them the 

 generic name of Prokoenenia, including 

 P. whederi, Eucker, from Texas, and P. 

 chilensis, Hansen, from Chili. The others, 

 styled by that author Eukoenenia, have 

 no lung-sacs. There are about ten 

 species, mostly from the Mediterranean 

 region, but E. augusta, Hansen, is found 

 in Siam, E. Jlorenciae, Eucker, in Texas, 

 and E. grassii, Hansen, in Paraguay. 



Order V. Solifugae (Solpugae). 



Tracheate Arachnids, ivith the last three 

 segments of the cephalothorax free and the 

 abdomen segmented. The chelicerae are 

 largely developed and chelate, and the 

 pedipalpi are leg-like, possessing terminal 

 sense-organs. 



The Solifugae are, in some respects, Fiq. 216.— Koemnia mna- 

 the most primitive of the tracheate 

 Arachnida. Their general appearance is 

 very spider -like, and by the old writers they are uniformly 

 alluded to as spiders. The segmented body and the absence of 

 spinning organs, however, make them readily distinguishable on 

 careful inspection. They are for the most part nocturnal 

 creatures, though some seem to rove about by day, and are even 

 called " Sun-spiders " by the Spaniards. The night-loving species 

 are attracted by light. They are, as a rule, exceedingly hairy. 

 Some are extremely active, while the short -legged forms (e.g. 

 Rhagodes, see p. 429) move slowly. They are capable of pro- 

 ducing a hissing sound by the rubbing together of their chelicerae. 

 Only the last three pairs of legs are true ambulatory organs, the 



» Quart. J. Micr. Sci. xlvii., 1904, p. 215. 



hiiis, much enlarged. 

 (After Hansen.) 



