SCOKPIONIDEA. 



799 



legs, the first two with gnathobases ; the first mesosomatic segment 

 bears the genital operculum, and the second the pectines, the 

 next four two lung -books ; the five posterior segments are 



FIG. 518. A Dorsal view of an Indian scorpion, Scorpio swammerdami x f. B Ventral, 

 view of the samex . A 1 Chelicera ; 2 pedipalp ; 3, 4, 5, 6 3rd to 6th appendages, or 

 walking legs ; 7 lateral eyes ; 8 median eyes ; 9 soft tissue at side of body, pleura ; 10 the 

 poison sting or telson. B 1-6 as in A ; 7 the genital operculum ; 8 the pectines ; 9, 10, 11, 

 12 the four right stigmata leading to the four lung-books ; 13 the last segment of the meso- 

 soma ; 14 the third segment of metasoma ; 15 the telson. In each case the metasoma, which 

 is usually carried bent forward over the meso- and pro-soma, has been straightened out. 



compressed and form a tail which ends in a post-anal sting 

 provided with poison glands. 



Scorpions are amongst the oldest of living animals of 



