503 



ARACIIXIDA. 



eleven segments and no jointed aiial filament. Ph. rtniforniix Latr., in Brazil. 

 ThflyjrttoHUs Latr. The chelicerae 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. caudatus Fabr., in Java. 



Order 6. SCORPIONIDEA* (SCORPIONS). 



Arachnida with chelate chelicerce, and elongated, pediform chelate 

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

 elongated post-abdomen of six segments, with 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 prse-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- 

 cerse 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, " Remarques sur la famillc des Scorpions et description de 

 plusieurs especes nouvelles, etc." Arch. <lu mum'-i- </'/<i*t. nut.. IV. Newport, 

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

 Systems in Myriapoda and macrourous Arachnida," Phil. Trait*. 184:?. 

 L. Dufour, " Histoirc anatomiquc et physiolngique des Scorpions," Mun. pres 

 a Tacad. des sciences, XIV., 18o6. E. Metschnikoff, " Embryologie des Scor- 

 pions," Ztiitscli r far miss., Zool., 1870. 



F:o. 410. Cephalo-thorax and pra?-aMomen of 

 Scorpio africanut (re;;ne animal). A"/, Cheli- 

 ceras ; AY, pedipalpi ; K, pectines ; St, 

 stigmata. 



