616 



ZOOLOGY 



SECT. 



thorax is not constricted off 

 from the abdomen. The cheli- 

 cerse are chelate, the pedipalpi 

 short and leg-like, the legs 

 long and slender. 



In the Acarida or Mites 

 and Ticks (Figs. 508 and 509) 

 the distinction into regions is 

 no longer recognisable. The 

 form of the mouth parts varies 

 somewhat in the different 

 families. Sometimes the basal 

 portions of the pedipalpi form 

 a sucking proboscis enclosing 

 the stylet-like chelicerse, modi- 

 fied to form piercing organs ; 

 sometimes these appendages 

 are claw-like or chelate. The 

 legs vary somewhat in shape in the different groups, according 

 as they are used for prehension, for creeping, for running, or 



FIG. 508. Itch mite (Sarcoptes scabisei). 



(After Leuckart.) 



FIG. 509. Water mite. Trombidium fuliginosum, female, chel. chelicerse ; ped. pedipalpi 



(After Leuckart.) 



for swimming; they end usually in two claws, between which 

 there may be discs or stalked suckers. 



