THE ARTHROGASTRA. 



321 



which correspond with the third, fourth, fifth, and sixth, of 

 the free terga. Each of these bears a pair of oblique slits, 



Fig. 84.— Scorpio afer.—A, tersral, and B, sternal, view of the body ; At, chelicerae ; 

 iv', pedipalpi ; v', vi', posterior pair of cephalic appendages ; vn', vin', anterior 

 thoracic limbs; Pt, pectines ; St, stigma; Cth, cephalo-thorax. (After Milne- 

 Edwards and Duges. 1 ) 



which are the openings of the respiratory organs (Fig. 85, e). 

 The sterna of the first and second free somites (ix, x) are very 

 small ; that of the first carries the valves which cover the 

 genital aperture ; that of the second bears a pair of very 

 curious appendages, somewhat like combs, which are termed 

 the pectines. The nervous trunks which enter the pectines 

 are distributed to the numerous papillae which cover them, 

 and are probably tactile in function. Thus there are twelve 

 somites behind the eye-bearing shield, and none of these are 

 provided with appendages, unless the pectines be such. 



The truncated anterior extremity of the body, beneath the 



1 " Regne Animal," Illustrated Edition. 



