CHAPTER XII 



AltACHNIDA (COXTIXUED) - EMBOLOBKANCHIATA - SCORPIONIDKA- 



PEDIPALl'I 



SUB-CLASS II. EMBOLOBKANCHIATA. 1 



Order I. Scorpionidea. 



Xrgmeiited Arachnids with chelate chelicerae and jifi!ijm//>i. 

 The abdomen, which is broadly attached to the cep)i<iltitln>r.i- or 

 prosoma, is divided into two regions, a six-jointed mesosoi/ia. ////</ a 

 *i ''-/ni nted tail-like metasoma, ending in a poison-sting. Th<r<- 

 are four pairs of lung-books, and the second ///>'x< <///*///> *<</, // n/ 

 bears n />// </' cum/i-fike organs, the pectines. 



THE Scorpions include the largest trachea! e Arachnid forms, 

 and show in sonic respects a high grade of organisat inn. ll is 

 impossible, however, to arrange the AiMchnida satisfactorily in ;m 

 ascending series, for certain primitive characteristics are often 

 most marked in those Orders which on oilier grounds would seem 

 entitled to rank at the head of the group. Such a primiti\c 

 characteristic is the very complete! segmentation exhibited h\ the 

 Scorpions. They are nocturnal animals of rapacious habit. In 

 size they range from scarcely more than half an inch to ei-hi 

 inches in length. In the northern hemisphere they are nut 

 found above the fortieth parallel of latitude in the Old \\'urld. 

 though in the New World they extend as hi'jh as the fri \ -lil'lh. 

 corresponding southward limit, would practically include 

 all the land in the southern hemisphere, and here the Order is 

 universally represented exec] )t in New Zealand, Sout h I'a 

 and the Antarctic islands. 



1 Cf. i>. 258. 

 297 





