124 



NATURAL HISTORY OF ARTHROPODS. 



of the world, are nocturnal in their habits, hiding during the day under stones, etc. 

 They are very active and pugnacious, and are reputed to be very venomous, but the 

 effects of their bite are probably considerably exaggerated. Solpuga araneoides, a 

 very hairy species, is found in the region of the Volga. 



SUB-ORDER, IV. - - PSEUDOSCORPII. 



As their name indicates, these small forms closely resemble the true scorpions in 

 appearance, but one important distinction is at once noticeable ; the long and slender 

 termination of the abdomen with its poisonous sting is absent. The chelicerae are 

 rudimentary and fitted for sucking, while the palpi are large and stout, each terminating 



/ ' ^^m 



"VJ ff^^~. 



FIG. 180. Solpuya araneoides. 



in a pincer as in the true scorpions. Two or four or no ocelli are present, and the 

 abdomen is eleven jointed. They breathe by means of tracheae. 



Nine genera, represented by forty living and eleven fossil species, are known, but 

 in the United States only the genera Chelifer, Chernes, Chthonius, and Obisium, with 

 nine species, have been found. The fossil forms occur in amber and copal, and one 

 species has been found in the coal formations. These forms are all small, none exceed- 

 ing a few lines in length. They occur under moss and bark of trees, and one species 

 at least (Chelifer cancroides} is not uncommon in houses and books. They are fre- 

 quently found attached to insects, especially to flies, but whether this is from a parasitic 

 habit or from a desire for a more rapid locomotion is uncertain. The probabilities are 

 in favor of the latter. The food is supposed to be the juices of other insects, for which 

 their sucking mouth-parts especially adapt them. 



