AEACHNIDA. 



155 



surface of the abdomen by as many distinct apertures or si)ira 

 (tig. 101, C). 



The Scorpions live in the warmer regie ms of the tempeiute ; 

 and in tropical countiles, and are 

 generally found hiding under 

 stones or in the crevices of walls. 

 They live upon insects, which 

 they catch with the great nipping- 

 claws, and sting to death witli the 

 telson. 



Related to the true Scorpions, 

 though belonging to a sjiecial 

 group, are the little " Pseudo- 

 scorpions " or " Book-scorpions " 

 (fig. 103, A). These are small 

 Arachnidans, which are common- 

 ly found among old books, and 

 which look very like Scoi'pions in 

 miniature, tliis being due to the 

 fact that the maxillary palpi are 

 of great size and terminate in 

 pincers. Related to these, again, 

 are the " Harvest-men " (I'/ial- 

 (ingimn, tig. 103, B), which are 

 drstingiushed by the great length 

 and slenderness of their legs. 



Order IV. Araskida. 



In this order are the true Spidei-s, i-eadily distinguished from the 

 Insects, with which they are popularly confounded, by having four 

 pairs of legs, as well as liy other characters. In all the true .Sjjiders 

 (fig. 104) the segments of the thorax and head are united to form a 

 single mass or cephalothorax, to which the soft and unsegmented 

 abdomen is joined by a constricted stalk or neck. Respiration is 

 effected by means of pulmonary sacs, conjoined with tracheje. The 

 pulmonary .sacs are two or four in nuniljer, and ojien on the vuider 

 surface of the abdomen by as many ajiertures. The head bears 

 from two to eight simple eyes ; the mandibles (tig. 104, B) are 

 hooked, and carry the duct of a poison-gland ; and the maxillary 

 palpi are not developed into nipping-claws. The Spiders are all 

 predacious and rapacious animals, and many of them possess the 

 power of constructing webs, either for the capture of their prey, or 



