CHARACTERISTICS OF INSECTS AND THEIR RELATIVES 9 



CLASS ARACHNIDA 

 .Scorpions, Harvestmen, Spiders, Mites, and others 



The members of this class are air-breathing arthropods, in which the 

 head and thorax are usually grown together, forming a cephalothorax, 

 which have four pairs of legs, and which apparently have no antenna. 

 The reproductive organs open near the base of the abdomen. 





Fig. i i b 



Fig. ii. Arachnids: a, a scorpion; b, a harvestman. 

 c, a spider; d, an itch-mite, from below and from 

 above. 



The Arachnida abound wherever insects occur, and are often 

 mistaken for insects. But they can be easily distinguished by the 

 characters given above, even in those cases where an exception occurs 

 to some one of them. The more important of the exceptions are the 

 following : in one order, the Solpugida, the head is distinct from the 



