348 ARACHNOIDEA. 



CASE five-jointed" (as shown in the. above woodcut, copied from Dr. 

 Low's figure), "which five joints comprehend the coxa, femur, a 



Tail of Phytoptus. 



very short tibia, and two-jointed tarsus. The terminal joint of 

 the tarsus, which is longer than its first, and somewhat knobbed 

 at the end, bears a long round claw, which is only a little thickened 

 and obtusely rounded at the tip. Beside this claw, inclined 

 towards .the inner side, is a feathered organ for holding on by, 

 which has on each side five gradually diminishing branches." 



Claw of Phj-toptus (Typhloch-omus) pyri. Claw of Phytoptus (Flexipalpus) tiliEe. 



Copied from Sdeuteii. Copied from Scheuten. 



This "haftorgan," or boat hook, as it were, differs in different 

 species. The two figures taken from Scheuten, which we here 

 give, show respectively its different forms in the different Phytopti 

 specified under each, viz., with one hook in Typhlodromus pyri, 

 two in Flexipalpus tiliae, and there are five in that of the gall 

 of Bromus mollis. We are strongly inclined to suspect that 

 the right interpretation has not been put upon these organs. 

 What does the animal want with another soft claw alongside 

 the harder boat-hook? As we read it, the boat-hook is the 

 claw, and the longer so-called claw is a sucker, like those of 

 the Sarcoptidse. We can point to an exact parallel to this ar- 

 rangement of sucker and claw, and nearly in the same pro- 

 portionate dimensions, in the termination of the leg in Symbiotes 

 bovis, and Psoroptes equi among the Sarcoptidse (see the wood- 

 cuts of these species). Again, the reader knows that it is an 

 almost universal peculiarity of the Sarcoptidae (so much so, that 

 we have used it as a family character) to have the body finely 



