INSECTS AND THEIK NEAR RELATIVES. 



15 



AA. Abdomen unsegmented. 



B. Abdomen joined to the cephalothorax by a short, narrow stalk. 



{Spiders.) p. 20 Araneida. 



BB. Abdomen fused with the cephalothorax. {Mztes.) p. 42. 



ACARINA. 



Order SCORPIONIDA (Scor-pi-on'i-da). 

 The Scorpions, 



With the scorpions (Fig. 8), the body is divided into a 

 compact, unsegmented cephalothorax, and a long, segmented 

 abdomen. The abdomen is divided 

 into two portions : a broad pre-abdo- 

 men, consisting of seven segments ; 

 and a slenderer tail-like division, the 

 post-abdomen, consisting of five seg- 

 ments. At the end of the post-abdo- 

 men there is a large poison-sting, 

 which appears like a segment. The 

 mandibles and the palpi are provided 

 with pincers. As the palpi are very 

 large, with stout pincers, they resem- 

 ble in a striking manner the great claws 

 of lobsters. The cephalothorax bears 

 from three to six pairs of eyes. Scor- 

 pions breathe by means of lung sacs, 

 of which there are four pairs, opening 

 on the lower side of the third to the 

 sixth abdominal segments. 



Full-grown scorpions possess a pair of comb-like organs 

 on the lower side of the second abdominal segment. The 

 function of these organs is not yet known. 



The sexes of scorpions differ in that the male has 

 broader pincers and a longer post-abdomen. Scorpions do 

 not lay eggs, the young being developed within the mother. 

 After the birth of the young, the mother apparently shows 

 great regard for them, carrying them about v/ith her for 



Fig. 8.— A Scorpion. 



