508 



ARACIINIDA. 



eleven segments and no jointed anal filament. PJi. n-nifnrm-is Latr., in Brazil. 

 Tlii-1 i/plioniis Latr. The cheliceras are short and end in a chela, their masti- 

 cating blades fuse in the middle line. The elongated twelve-ringed abdomen 

 with segmented anal filament. T. cinulfttiix Fabr.. in Java. 



Order 6. SCORPIONIDEA* (SCORPIONS). 



Arachnida vuith chelate chelicerce, and elongated, p&llforni chelate 

 pedipalpi, with a prce-abdomen composed of seven segments, and an 

 elongated post-abdomen of six segments, toith poison spine at the hind 

 end ; with four pairs of lungs. 



The Scorpions have a cer- 

 tain resemblance to the De- 

 capod Crustacea in their 

 powerful chelate pedipalpi and 

 firm armour (fig. 410). The 

 stout cephalo-thorax is joined 

 to an elongated abdomen, 

 which is divided into a cylin- 

 drical pne -abdomen, composed 

 of seven segments, and a very 

 narrow six-segmented post- 

 abdomen, which is curved 

 dorsalwards. The post-abdo- 

 men ends with a curved poison 

 spine, which is provided with 

 two poison glands. The cheli- 

 cerfe are three-jointed and 

 chelate ; the pedipalpi end 

 with a swollen terminal 

 chela, while the basal joint 

 serves with its broad grinding 

 surface as a jaw. The four 

 pairs of legs are strongly de- 

 veloped and end with double 

 claws. 

 In their internal organization the Scorpions reach the highest 



* P. Gervais, " Eemarqnes sur la famille des Scorpions et description de 

 plusicurs especes nouvelles, etc.' ? Arcli. <ln untser irhixt. tint.. IV. Newport, 

 " On the structure, relations, and development of the nervous and circulatory 

 Systems in Myriapoda and macrourous Arachnida." Phil. Trans. 1843. 

 L. Dufour, " Histoire anatomique et physiologique des Scorpions," Mem. pros 

 a Tiiriul . il<>s srinu-rx, XIV., 1S56. E. Metschnikoff, " Embryologie des Scor- 

 Sj" Zeltxc h rf/ir irixx.. ZnnJ ., 1870. 



St 



FIG. 410. Cephalo-thorax and pre-abdomen of 

 Scorpio africanus (ivu'ne animal). Kf, Cheli- 

 cera? ; Kt, pedipaljii ; i", jjectines ; fit, 

 stigmata. 



