JOURNAL 



jOffD iHoph €lnfoniolQgiraI %mM^. 



Vol. XIX. JUNE, 1911. No. 2. 



NOTES ON PSEUDOSCORPIONS; A STUDY ON THE 



VARIATIONS OF OUR COMMON SPECIES, 



CHELIFER CANCROIDES LINN., WITH 



SYSTEMATIC NOTES ON OTHER 



SPECIES. 



By H. E. Ewing, 

 Ames, Iowa. 



(With Plates I to V.) 



Introduction. 



The pseudoscorpions constitute a small though well-defined group 

 of the class Arachnida. They are typically arachnid in the posses- 

 sion of : first, a fused anterior portion of the body called the cephalo- 

 thorax; second, in the organization of their mouth-parts; and third, 

 in the possession of four pairs of legs. The pronounced segmenta- 

 tion of the abdomen, the constant possession of chelate chelicerae, 

 the enormous development of the palpi, and the frequent absence of 

 eyes are characters which would indicate their position among the 

 more primitive members of x\rachnida. On the other hand, the pres- 

 ence of an elaborate system of branched, tubular tracheae as well as 

 the presence of spinning organs show that they differ essentially from 

 the most primitive of the living members of the class. 



The group is one that has never been very extensively studied. 

 Prominent among the European workers might be mentioned : Menge, 



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